FORT WORTH (CBSDFW.COM)- Federal investigators say the warning signals at a railroad crossing activated 20 seconds before a float crossed the tracks in a parade that killed four military veterans and injured 16 others.

Mark Rosekind, a member of the National Transportation Safety Board, said a front facing camera on the locomotive engine and dash cam video from a police cruiser revealed the new information.

Rosekind said it was clear that the warning lights and signals were working properly before the crash.

“We don’t know if the timing and synchronization was correct or not. That’s part of what we are still doing,” he said.

Investigators outlined a timeline leading up to the crash.

Rosekind said 13 seconds before the impact, the gates started coming down. At 12 seconds, the truck crossed the front rail. At nine seconds, the train engineer sounded his warning horn. At seven seconds, the gate hit the float. Finally five seconds before the crash, the engineer hit the emergency brake.

The train did not come to a complete stop until 75 seconds later.

Travis Reichert, a war veteran from Wisconsin, was sitting at the end of the float.

“I stood up and I looked and I saw the train right there so I yelled for everyone to jump off the trailer,” he said.

A few people reacted in time, including his wife, but 16 people were injured and four veterans died in the horrific crash.

Reichert said they used their military training to jump into action.

“Service members were already doing CPR. One guy took his shirt off and was using it as a tourniquet,” he said.

Rosekind said they’ve conducted 40 interviews and plan on doing more. The driver of the float has yet to be interviewed but investigators say they have made contact with the trucking company.

Though details are emerging slowly, investigators say many unanswered questions still remain.

“There’s a lot of other information that we need to get about the requirements of having a parade, of what notification was given to the railroad, what the specific plan was that the police had for the route, the activities, of the escorts, etc,” said Rosekind. “All of that will be looked into to see what role they might have played in the accident.”

Investigators determined the train nor the tracks had any defects. They plan to conduct a sight distance test Monday morning.