MIDLAND, Texas (AP) -- With the thunderous crack of a freight train slamming into a parade float carrying his fellow war veterans, Sudip Bose went to work.
A front-line physician in Iraq, Bose and other veterans instantly tended to the injured. They applied tourniquets and put pressure on wounds as their training and battlefield experience took over in the chaotic moments after the wreck at a railroad crossing in this West Texas city.
"Instincts kicked in," Bose said Friday, a day after the train traveling at more than 60 mph barreled into a flatbed truck adorned with American flags and filled with wounded veterans and their spouses.
Four veterans of Iraq and Afghanistan were killed -- including an Army sergeant who apparently sacrificed his life to save his wife -- and 16 people were injured. Bose, who served in Fallujah and Baghdad, said the aftermath reminded him of a combat triage situation.
Some of the veterans who managed to jump clear of the wreck rushed to help the injured. Tommy Shoemaker, a special operations soldier, resuscitated one person and applied a tourniquet to a bleeding woman.
"They are trained for tragedy," said his wife, Pam Shoemaker of Monroe, La., who was with her husband on a float ahead of the one that was hit.
Killed were Marine Chief Warrant Officer 3 Gary Stouffer, 37; Army Sgt. Maj. Lawrence Boivin, 47; Army Sgt. Joshua Michael, 34; and Army Sgt. Maj. William Lubbers, 43.
Five people remained hospitalized early Saturday. In Midland, three people were in stable condition and one in critical. None of the injuries are life-threatening, said hospital spokeswoman Marcy Madrid. A fifth person, who had been transferred to a Lubbock hospital shortly after the accident, is in serious condition.
At the time of the crash, the veterans were on their way to a banquet in their honor and being cheered on by a flag-waving crowd. Their float was inching across a railroad track in Midland when the crossing gates began to lower.
Some of those seated on the float jumped off just moments before the train seemed to appear out of nowhere and crashed into the truck.
Michael, one of the soldiers killed, pushed his wife off the float when he saw the train coming, his wife told Cory Rogers, a friend of the couple.
"His first instinct was to get her out of harm's way," said Rogers, who was not at the parade. "That's the kind of man he was, and I feel like it was his training as a paramedic and then as a soldier, choosing to put someone's life before your own."
Locals were struggling to cope with a tragedy at the start of what was supposed to be a three-day weekend of banquets, deer hunting and shopping in appreciation of the veterans' sacrifice.
"It's just a very tragic and sad thing," said Michael McKinney of Show of Support, the local charity that organizes the annual event and invited the veterans. "It's difficult when you're trying to do something really good and something tragic occurs."
Federal investigators were trying to determine whether the two-float parade had been given enough warning to clear the tracks.
National Transportation Safety Board member Mark Rosekind offered hope Friday that video would provide a fuller picture of what happened. Cameras were on both the lead car of the train and a sheriff's vehicle that was trailing the flatbed truck, Rosekind said.
The train was moving at 62 mph at the time of the crash, short of the 70 mph speed limit, Rosekind said. The speed limit was raised from 40 mph in 2006, Union Pacific spokeswoman Raquel Espinoza said.
Rosekind also said Friday that the truck driver voluntarily submitted to blood tests.
On Saturday, officials from the NTSB, the Federal Railroad Administration and Union Pacific were at the crash site conducting tests and taking pictures. They were inspecting the crossing gate, measuring distances and testing the crossing's warning bells. Officials declined to comment, referring all questions to spokespeople.
Makeshift memorials had popped up at the crash site, with some American flags and flowers visible. Mayor Wes Perry said a candlelight vigil is planned in downtown Midland on Saturday night.
Shoemaker said the flatbed truck she was riding on had just crossed the tracks and was moving slowly when she heard a train coming and looked back to see the lowered crossing gates bouncing up and down on the people seated on the float behind her.
Witnesses described people screaming as the warning bells at the crossing went off and the train blasted its horn.
Daniel Quinonez, who was waiting in his vehicle as the parade went by, said the float on the tracks could not go anywhere because of the one right in front of it.
"It was a horrible accident to watch happen right in front of me," he said.
Another witness, Joe Cobarobio, said only a few seconds elapsed between the time the crossing gates came down and the train slammed into the flatbed truck with a "giant cracking sound."
Federal Railroad Administration records reviewed by The Associated Press show there were 10 collisions at the crossing between 1979 and 1997. But no accidents had happened in the past 15 years, the NTSB's Rosekind said.
A key question for investigators is whether, after the speed limit was raised, the timing of the crossing gates was changed to give cars and trucks enough time to clear the tracks, Robert Chipkevich, who headed NTSB's rail investigations unit until 2010, said in an interview.
Investigators also will look at whether traffic lights prevented the flatbed truck in front from moving ahead, he said.
Associated Press writers James Beltran, Nomaan Merchant, Danny Robbins and Terry Wallace in Dallas; Angela K. Brown in Fort Worth, Texas; and Joan Lowy in Washington contributed to this report.