BRANSON, Missouri (CNN) - State investigators looking into the sinking of a duck boat in southwestern Missouri that killed 17 people -- including nine from one family -- want to know why the vessel changed the route it took that day, Missouri Attorney General Josh Hawley said Saturday.
The amphibious vessel, which had 31 people aboard, was sailing Thursday on Table Rock Lake near Branson when a severe thunderstorm whipped up intense winds and waves.
The state is looking into the incident to see whether any criminal acts were committed, Hawley said, while the National Transportation Safety Board is investigating to determine the cause of the sinking.
The attorney general said companies need to have procedures in place to deal with bad weather.
Investigators want to know "when did the driver and (captain) of this vessel know about this storm forecast? When did they decide to alter the route of the boat?" he said. "Because they did alter the route of the boat. When did they decide that? Why?"
Hawley could not say whether investigators had spoken with the captain, one of 14 survivors. The driver died in the sinking.
Tia Coleman, a passenger on the boat who was sitting near the front, told reporters Saturday that passengers were told a storm was coming before going out on the water.
She said when the boat first got on the water, it did not look cloudy.
The attorney general said investigators from the Missouri State Highway Patrol will also look at the boat's canopy and how difficult it was for the passengers and crew to get off during the chaotic event.
"I certainly have concerns about the ability to exit the vessel, to get out of it in an emergency situation." he said.
The NTSB investigation into the sinking could take up to a year to complete, Earl Weener said Friday.
Saturday, Weener said the NTSB has received outstanding cooperation from Ripley Entertainment Inc., the parent company of the duck boat business.
Calm day turned stormy
CNN asked Ripley President Jim Pattison Jr. on Friday what the crew knew about the thunderstorm warnings when the tour embarked.
"My understanding was that when the boat went in the water, it was calm," Pattison told CNN's "New Day." "And partway through coming back is when ... the waves picked up and then obviously swamped the boat."
A tour lasts about 70 minutes, with about half on land and half on water, the company's website says.
The boat sank 40 feet and then rolled to an area 80 feet deep, Stone County Sheriff Doug Rader said.
Life jackets were on the boat, but there is no regulation mandating that duck boat passengers wear them, Pattison said Friday.
Asked whether passengers were able to access them, Pattison said: "We don't know that yet."
A severe thunderstorm warning
According to weather data, the storm traveled hundreds of miles before it hit the lake, prompting severe-weather alerts as it moved along.
Counties to the northwest of the Branson area were issued thunderstorm warnings at 5:45 p.m. -- more than an hour before the boat sank. The Branson area was placed under a severe thunderstorm warning shortly after 6:30 p.m.
Radar shows the first wind gusts arriving at the lake ahead of the storm, at 6:59 p.m. Authorities received the first 911 call about the boat's sinking at 7:09 p.m., the sheriff said.
The storm was part of the same upper-level weather system that produced damaging wind gusts earlier Thursday in Kansas and spawned destructive tornadoes in Iowa.
Attorney: 'They are death traps and sinking coffins'
Duck boats travel on both land and water and are popular among tourists in major cities. The boats' history dates to World War II, when such vessels were a common sight because of their versatility.
In Branson, a popular family vacation destination about 200 miles southeast of Kansas City, Missouri, they are driven along city streets for part of the tour before the driver uses a ramp to enter the lake.
Thursday's sinking in Missouri isn't the first time that trouble with these tour vessels have turned fatal. At least 39 people have died in duck boat accidents in the past 20 years. Accidents in and out of the water have marred their popularity and forced some companies to shut down their businesses.
The NTSB issued recommendations after one of those accidents -- the sinking of a duck boat in Hot Springs, Arkansas, in 1999. Thirteen of the 21 people aboard died.
The NTSB determined the vehicle sank because it took on water quickly and didn't have reserve buoyancy, meaning there was nothing to help it float. The agency said the boat's canopy was a major impediment to the passengers' survival.
Of the seven people found dead inside the vehicle, four were found trapped in the canopy.
The board recommended that amphibious vehicles be retrofitted for reserve buoyancy. Until those changes were made, the board recommended, all canopy roofs should be removed.
Further, the NTSB said if those vehicles weren't retrofitted and still had canopies, passengers shouldn't wear life jackets.
"The safety board is particularly concerned that both adults and children wearing life jackets are at risk of being drowned if entrapped by the overhead canopy," the report reads.
Friday, US Sen. Claire McCaskill, a Democrat from Missouri, said the recommendations were never enacted into law. She said she and her colleagues would take a look at legislation, possibly as early as next week.
"I'm not going to rest until we get something in the law on a national basis that does a better job of regulating the safety of amphibious vehicles," she told CNN on Friday.
Jeffrey Goodman, who has represented people injured in past duck boat accidents, said the vessels should be banned.
"They are dangerous on land and on water. They are death traps and sinking coffins," he told CNN.
The NTSB and multiple duck boat companies declined to comment on the safety issue.
Ride the Ducks Branson said it was deeply saddened and "will be closed for business while we support the investigation, and to allow time to grieve for the families and the community."
Mourners light candles for the victims
Dozens of people left flowers, cards and balloons at a vigil Friday at the Ride the Ducks building in Branson. Mourners lit candles around cars left in the parking lot overnight -- cars believed to belong to the victims.
"I look at my family here, and this could've been us," Ed Brown, who was at the vigil, told CNN affiliate KMIZ.
After all 17 bodies were recovered, the Stone County Sheriff's Office released the names of those who died.
Nine members of one extended family from Indiana -- all with the Coleman surname -- died.
Two others from that family were on the boat and survived: Tia Coleman and her 13-year-old nephew.
Coleman said at Saturday's news conference that she doesn't know yet whether she is happy she survived. But she thinks there is a reason she lived.
"God must have something for me because there's no way I should be here," she said.
Coleman said she knew she was in deep water because it was cold and she struggled to get the top.
"I said, 'Lord, please, I've gotta get to my babies. I've gotta get to my babies.' The harder I was kicking to the top, I was pulled down," she said.
Three of Coleman's children and her husband were among the dead.
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