"There was this loud bang, the buses shook, and everyone turned around," she said. "People were still suffering the after-effects of the run, and we only saw what looked like white smoke. Everyone thought it was some sort of celebration — like maybe a cannon."
The twin explosions that killed three and injured nearly 200 more came at around 2:45 p.m. Monday near the finish line of the race.
At a Tuesday press conference, Richard DesLauriers, FBI special agent in charge of the investigation, said that the explosions came from bombs — possibly pressure cookers stuffed with explosives and what appeared to be BBs and nails — that were placed in black nylon bags.
DesLauriers said in another conference Thursday that the FBI has identified two suspects from video and photos taken the afternoon of the bombing. Each of the two men were photographed wearing large black backpacks, and the second suspect was photographed setting a bag down in front of the Forum Restaurant on Boyleston Street, where the blasts occurred.
Trumbore, a Palo Alto resident, said it didn't occur to her or the other runners that something was wrong, partly because of the daze they were in and partly because many of the nearby volunteers didn't appear visibly alarmed. She heard sirens approaching the area but initially dismissed them because they aren't a particularly rare occurrence at the finish line of a marathon.
"You often hear sirens — at the end of a marathon people go to the hospital, get hurt or have heart attacks — but your brain doesn't immediately go to a bombing," she said.
It wasn't until 10 or 15 minutes after the blasts that she realized that something was seriously wrong. All the race volunteers began running toward the finish line, and the sirens grew more intense as she started hearing passers-by in cell-phone conversations mention the dead and injured.
Dr. George Velmahos of Massachusetts General Hospital in Boston said in a press conference Tuesday morning that several of the victims admitted to the trauma ward received amputations "because of the devastating effects of the bombs."
"Many have severe wounds, mostly in lower parts of the body, related to blast effects of bomb, as well as small fragments that entered the body: pellets, fragments, nails," he said.
Palo Alto resident Riya Suising said she was waiting in line at the marathon's complimentary massage booth about 45 minutes after completing the race when she heard the explosions.
"It sounded like thunder, but it was different," she said. "The staff told all the runners and massage therapists to evacuate. Then we knew it was serious."
Suising, who was three blocks away from the blasts, said she began hearing signs of the explosions, including sirens and the reactions of passers-by.
"I saw two ladies holding each other, crying, in tears, maybe about a relative," she said. "It turned out not to be a great day, but we're all very fortunate to be safe."
DesLauriers said the investigation "is in its infancy," but more than 1,000 law-enforcement officers from several agencies are chasing the more than 2,000 leads that have been received.
Twenty Palo Alto residents had signed up for the race. Some did not participate due to injuries. Half of those registered had completed the marathon prior to the bomb explosions. Numerous runners checked in with family and friends, or posted via social media, letting people know they were safe.
Palo Alto resident Jessica Williamsen confirmed Monday that she had finished about 30 minutes before the blasts occurred and that she and her family were well clear of the area.
Palo Alto resident Felice Kelly went to support her sister, Natalie, at the race. She followed her sister through a late portion of the race until the crowds were too thick for her to continue.
After Natalie crossed the finish line at around 2 p.m., the two sisters went to get a sandwich about three blocks away when someone ran in, saying that shots had gone off.
Neither of the sisters, nor Menlo Park resident Laura Blaich, heard the blasts. Blaich was also about three blocks away at a public-transportation station.
Kelly said she worries about the effect the blasts will have on the sport.
"In a weird way I hope it doesn't change marathons, partly because they're public and open and free — there's a bit of risk you have to accept."