HOUSTON -

Hundreds of teens were forced to run for their lives after a gunman opened fire at a high school party.

According to the Harris County Sheriff's Office, the students were having an after-prom party around 1:35 a.m. Saturday at a horse barn located at Gears and Trickey Road.

Deputies said the party had anywhere from 200-300 teenagers from three different schools.

In the early morning hours, a group of males who were not invited to the party but saw the post on social media, showed up. After some sort of disagreement, investigators said adult chaperones asked the males to leave.

"They were told they couldn't stay, they were asked to leave. As they were walking out, they got into a car and one of the suspects produced a long gun and fired several rounds," said Sgt. Thomas Gilliland, a spokesperson for the Sheriff's Office.

According to reports, the shooter may have also used a handgun after using the rifle. In the chaos, students rushed to leave the scene, spilling into the street in front of the barn.

Witness Alexander Rooke said he was driving through the area and saw a crowd of students running into the roadway.

"I looked in my rear-view mirror. I could see people running from the field and as they were running, all you could hear was gunshot, gunshot, gunshot. It was crazy. A lot of gunshots. It sounded like a fully automatic rifle letting off in this area," said Rooke.

Investigators said up to seven people were shot, including an adult chaperone who was shot in the lower back and taken to Ben Taub Hospital in critical condition. The other injuries were described as minor. All of the victims are expected to survive.

While some were still at the scene when deputies arrived, others were taken to the hospital in private vehicles, making it difficult for investigators to tally up the total number of victims.

Westfield High School Senior Cynsean Yancy was grazed by a bullet as he tried to leave. He said he decided to leave the party after people started yelling gang names.

Yancy said as he made it his car, the gunfire began. He was able to get inside and then reclined his seat to take cover, waiting for the gunfire to stop. When it didn't, Yancy said he started to get up and drove away, but in the process a bullet pierced his driver's side window, grazing his head.

"There was blood all over my face. Nobody knew how bad it was and exactly what happened," said Yancy.

Dazed, Yancy made it to a parking lot across the street where friends picked him up and rushed him home. His parents then called an ambulance and Yancy was taken to a hospital to be treated.

"This could be funeral arrangements for me. I just feel blessed to be here. I just thank God I'm alive," said Yancy.

Yancy's car was also damaged when another student crashed into him, also trying to dodge the gunfire.

Deputies were told by numerous witnesses that there was only one shooter and confirmed that the incident may have been gang related. So far, no arrests have been made but investigators said they are following leads and have an idea of who may be responsible.

Investigators said the party was thrown by a high school student's parents and there were adult chaperones in attendance. They found no evidence of alcohol or illegal activity.