The head of the Department of Homeland Security says "there appears to have been 1 gunman" in the attack that killed five Dallas police officers and wounded seven others.
Micah Johnson, an Army veteran killed by Dallas police after the sniper slayings of five officers during a protest march, told authorities that he was upset about the police shootings of two black men earlier this week and wanted to exterminate whites, "especially white officers," officials said Friday.
Johnson, 25, was a part of the Houston chapter of the New Black Panther party a few years ago. According to community activist Quanell X, Johnson was only a member for about 6 months. Quanell X said the group had issues with Johnson, who didn't want to follow the chain of command.
Johnson was killed by a robot-delivered bomb after the shootings, which marked the deadliest day for U.S. law enforcement since the Sept. 11, 2001, terrorist attacks. In all, 12 officers were shot.
Homeland Security Secretary Jeh Johnson said at a news conference Friday in New York City that Micah Johnson doesn't appear to have had any known "links to or inspiration from any international terrorist organization."
Dallas police say Johnson had bomb-making materials, ballistic vests, rifles, ammunition, and a personal journal of combat tactics at his home.
They also say that people they interviewed have described Johnson as a loner.
They say detectives are in the processing of analyzing the information contained in the journal.
Johnson was a private first class from the Dallas suburb of Mesquite with a specialty in carpentry and masonry. He served in the Army Reserve for six years starting in 2009 and did one tour in Afghanistan from November 2013 to July 2014, the military said.
After the attack, he tried to take refuge in a parking garage and exchanged gunfire with police, Police Chief David Brown said.
Police killed Johnson with a robot-delivered bomb early Friday after negotiations for his surrender failed.
"We saw no other option but to use our bomb robot and place a device on its extension for it to detonate where the suspect was," Brown said. "Other options would have exposed our officers to grave danger. The suspect is deceased as a result of detonating the bomb."
Johnson had no criminal record or known terror ties, a law enforcement official said.
He had served in the U.S. Army Reserve, training as a carpentry and masonry specialist, two U.S. defense officials said.
A neighbor said there are police cars outside Johnson's home. Wayne Bynoe, the neighbor, told CNN that Johnson lived with his mother and "keeps to himself."
The Dallas police chief told reporters it's too soon to speculate on the suspect's motives, and it's unclear whether more suspects are on the loose.
A black SUV found at the scene of the shootings was listed as registered to Delphene Johnson, also of Mesquite.
Five police officers were killed and seven others were injured in the ambush in Dallas that began Thursday night, officials have said, in the deadliest single incident for U.S. law enforcement since the Sept. 11, 2001, terror attacks when 72 officers died, according to the National Law Enforcement Officers Memorial Fund. Two civilians also were injured in the shootings, the office of Dallas' mayor has said.
Among the victims is Dallas Area Rapid Transit officer Brent Thompson, 43, Dallas police officers Michael Krol and Patrick Zamarripa, who all died in the shooting. DART officers Misty McBride, 32, Omar Cannon, 44, Jesus Retana, 39, were injured in the shooting and a mother who was trying to shield her children from gunfire, Shetamia Taylor was also injured.
Most of the injured Dallas police officers have been released from a hospital, Brown told reporters. The officers' conditions are improving, Brown said.
"All I know is that this must stop -- this divisiveness between our police and our citizens," Brown said. "We don't feel much support most days. Let's not make today most days. Please, we need your support to be able to protect you from men like these, who carried out this tragic, tragic event."
Brown said an investigation into the ambush continues.
"I'm not going to be satisfied until we've turned over every stone. We've got some level that this one suspect did do some of the shooting. But we're not satisfied that we've exhausted every lead," he said. "So if there's someone out there who's associated with this, we will find you, we will prosecute you, and we will bring you to justice."
According to police, the captured suspects are not cooperating with authorities or answering questions.
Gunfire rang out Thursday night as demonstrators marched against the shooting deaths of two African American men by police in Louisiana and Minnesota.
Dallas Police Chief David Brown told reporters the snipers fired "ambush style" upon the officers. Police later said in a statement that a suspect who was in a shootout with Dallas SWAT officers was is in custody and a person of interest had surrendered. They said a suspicious package was being secured by a bomb squad.
A Dallas Police Department detective confirmed to NBC 5 in Dallas one suspect is dead and three other suspects were in custody in connection with the shooting. Two suspicious devices have been found.
"The suspect told our negotiators that the end is coming," Brown said. The suspect at the garage also told negotiators more officers are going to get hurt, and that bombs are planted all over downtown Dallas.
K-9 units swept the area for possible bombs.
Dallas officials said no explosives were found after conducting primary and secondary searches for explosives.
Dallas Area Rapid Transit identified one of the fallen officers as 43-year-old Brent Thompson. He is the first DART officer killed in the line of duty. He joined DART in 2009.
Thompson got married just two weeks ago to a fellow transit officer, DART Police Chief James Spiller told CNN's "New Day" Friday.
The gunfire broke out around 8:45 p.m. Thursday while hundreds of people were gathered to protest fatal police shootings this week in Baton Rouge, Louisiana, and suburban St. Paul, Minnesota.
Brown says snipers shot from "elevated positions" during a protest over two recent fatal police shootings.
Video footage from the scene showed that protesters were marching along a street in downtown, about half a mile from City Hall, when the shots erupted and the crowd scattered, seeking cover.
Witness Ismael Dejesus said he recorded the shooter from his hotel balcony about 50 yards away. He described the gunman as carrying a weapon with a "pretty big magazine."
Retired FBI special agent Steve Moore said an attack of that magnitude required advance work.
"This was an attack planned long before -- waiting for an opportunity to go," Moore said. "I think there was so much logistically, ammunition-wise. They may not have planned the location, they may not have planned the vantage point. But they had prepared for an attack before last night's shooting is my guess."
Four DART police officers were shot in downtown Dallas. 1 deceased, others not life-threatening. No IDs yet. Updates via twitter. — dartmedia (@dartmedia) July 8, 2016
All officers, ask to be placed in two man units and exercise extreme caution when responding to calls. WAIT for backup — HPOU (@HPOUTX) July 8, 2016
Scores of police and security officers were on hand. Police and others hunched behind cars outside a parking garage. Officers with guns drawn were running near and into the parking garage as police searched for the shooter.
What happened in Dallas tonite is inexcusable. I pray for the families of every police office that was killed or injured. st — Sylvester Turner (@SylvesterTurner) July 8, 2016
President Barack Obama, who is in Warsaw, Poland, said his team is keeping him updated. "We still don't know all the facts, we do know there's been a vicious, calculated and despicable act on law enforcement," Obama said. "I believe I speak for every American when I say we are horrified."
Gov. Abbott released the following statement on the shootings in Dallas:
"Our thoughts and prayers are with the Dallas law enforcement community and the Dallas Area Rapid Transit (DART) officers killed and injured this evening. I've spoken to Texas Department of Public Safety Director Steve McCraw and have directed him to offer whatever assistance the City of Dallas needs at this time. In times like this we must remember - and emphasize - the importance of uniting as Americans."
The shootings occurred as Americans across the nation vented their anger over the police killings of two black men in two days.
They chanted outside the governor's residence in St. Paul, Minnesota, miles from the spot where an officer killed Philando Castile in a car on Wednesday while a 4-year-old girl sat in the back seat.
Crowds milled in the streets outside the convenience store in Baton Rouge, Louisiana, where Alton Sterling was fatally shot while police grappled with him in a parking lot Tuesday.
Protesters briefly shut down the Dan Ryan Expressway in Chicago. In New York, 1,000 people marched down Fifth Avenue and a few scuffled with police officers.
They all came out to vent their rage at yet more slayings of black men at the hands of police officers.
"We are targets!" LaRhonda Talley said in an impassioned speech in Minnesota about the danger of being black in America. "We made it across the (Atlantic). We made it to freedom and you're still killing us. You're still hanging us from trees. You're still killing us! Our lives matter!"
The mighty also raised their voices.
President Obama talked about the shootings, saying "This is not just a black issue." Democrats came out as a group onto the steps of Congress to show their support for the victims.
Beyoncé, one of the most famous American pop stars, posted a message on her website, saying, "It is up to us to take a stand and demand that they 'stop killing us.'" The singer provided a link for fans to contact their congressmen.
Virtually every major city reported a gathering of some sort. Little violence was reported, but many tears were shed.
Valerie Castile, mother of Philando Castile, told a crowd gathered outside J.J. Hill Montessori Magnet School in St. Paul, where Castile worked, that somebody "needed to police the police."
"It was my son today but it could be yours tomorrow," she said. "This has to cease. This has to stop, right now."
She also urged an economic boycott to bring attention to the killings of black men. "The only thing they know is money," she said.
As has become the horrible norm, both killings were captured on video and posted online, helping the outrage spread across the country at lightning speed.
The shooting of Castile was remarkable -- and heartbreaking -- because it was live streamed by his fiancee, who calmly narrated the action and showed viewers the dying man groaning and bleeding in the front seat.
Castile, a school food services worker, was shot in Falcon Heights, outside St. Paul, when a police officer pulled him over because of a broken taillight, said his fiancee, Diamond Reynolds, who was in the car with Castile, along with her 4-year-old daughter.
"He let the officer know that he had a firearm and he was reaching for his wallet and the officer just shot him in his arm," Reynolds said as she broadcast the Wednesday evening shooting on Facebook. Later she says, "Oh God, please don't tell me my boyfriend is dead."
In interviews throughout the day, Reynolds complained that other officers responding to the scene were more concerned about the officer who fired the shots than Castile.
As news of Castile's killing spread, a crowd formed at Minnesota Gov. Mark Dayton's residence and grew throughout the day. Many ethnic groups were represented, including Aztec dancers who said they wanted to show the diversity of the community.
Among the protesters was Michael House, who said he grew up in the same neighborhood with Castile.
"I'm here because my longtime friend got killed by a police officer and we need justice out here," he said.
Sterling, 37, was killed Tuesday outside the Triple S Food Mart in Baton Rouge, where he regularly sold CDs and DVDs, earning the nickname "The CD man."
A source close to the investigation told CNN that problems started when a homeless man approached Sterling on Tuesday and asked for money, becoming so persistent that Sterling showed him his gun, the source said. "I told you to leave me alone," Sterling told the man, according to the source.
The homeless man called 911 and police arrived at the store. Sterling was tackled and taken to the ground, the video shows, and during the scuffle he was shot several times by police.
A law enforcement source with knowledge of the investigation told CNN that the officers pulled a gun from Sterling's body at the scene. No further details were provided on the type of firearm.
The convenience store quickly became the site of protests. Tokens, flowers and signs piled up in a makeshift memorial. Protesters chanted "Hands up, don't shoot," the line made famous in the Michael Brown shooting in Ferguson, Missouri, about two years ago.
A prayer vigil was held at a church. A minister urged anybody who carried a weapon to take it out of the sanctuary and store it in their car.
In New York, about 1,000 people marched up Fifth Avenue toward Union Square chanting "Black lives matter!"
They didn't have a permit, but police said they would allow the march to continue as long as it remained peaceful. Video later showed police scuffling with a few protesters but it wasn't known if anybody was arrested.