But no amount of training could have prepared veteran firefighter Pat Foley for the sight of mangled bodies blown apart by bombs on what should have been a joyous day.
"There was so much carnage," he told QMI Agency on Friday, describing last Monday as the worst day of his 34 years with the Boston Fire Department.
Foley was working a detail that required him to walk through the crowd near the Boston Marathon finish line -- mainly to check out any calls that came in and hopefully avoid having fire trucks dispatched to the area.
He and fellow firefighter Charlie Buchanan, who was working the same detail, met up near Fairfield and Boylston Sts. around 2:30 p.m., had a brief chat and walked off in opposite directions.
Minutes later, Foley saw an explosion.
"I thought it was a transformer, so I started running over there," he recalled. "I ran right into the second blast."
He was about 15 metres away when the second bomb detonated and narrowly escaped with his life.
"When that second bomb went off, there was no doubt in my mind," Foley said. "I knew it was a terrorist attack."
He remembers "a loud boom" and "lots of screaming" as people ran for their lives.
Foley had to fight his way through the fleeing throng as he ran toward the victims, many of whom were "reaching out for help" and "covered in shrapnel injuries."
"They had a look of pure panic on their faces," he said. "And there blood and body parts everywhere."
The first person he spotted was a man whose leg had been blown off.
"He was actually holding his leg and tried to pass it to me," Foley said.
The small first aid kit he had was of no use, so he asked a bystander to grab belts from people to use as tourniquets. He quickly wrapped one of the belts around the man's leg to try to stop the bleeding.
While using his knee to keep the make-shift tourniquet tight on the man's severed limb, Foley turned to a woman whose leg was torn off at the thigh and strapped a belt on her...