This story was reported by Andy Bromage and Kathryn Flagg

Peter Teachout was 100 yards from the finish line at the Boston Marathon when he heard a loud boom, then saw a huge puff of smoke.

"I thought it was a celebratory finish-line gun. Or maybe one of those World War 2 cannons they shoot off to celebrate the finish line," said Teachout, a Norwich resident and Vermont Law School professor. "We kept on running."

About 50 yards from the finish, just a few seconds later, the second bomb went off. At that point, Teachout said the runners in front of him turned around and started running toward him in panic. Teachout continued toward the finish — reflexively — until he saw injuried people lying in the roadway.

"They were clearly cut up," said Teachout, who was not injured in the blasts. "It really was surreal. It was like what you see in videos or films about terrorist attacks."

Teachout, 72, was one of 100 Vermonters registered in yesterday's 26.2-mile race. A longtime marathoner who once finished fourth in his age group at Boston, Teachout says he was having a "lousy" race. He lost a month of training owing to a recent surgery. He was on pace to finish somewhere around 4 hours and 8 minutes. Any faster, and Teachout might have been among the three dead and more than 100 injured in the bombings.

"I'm lucky I didn't run a minute faster," Teachout said by phone from his daughter's house in Boston.

Teachout said the first blast was larger than the second. "You're pretty tired at the end of a marathon and it doesn't fully register in a critical, realistic way because you're thinking about finishing," Teachout said. "There was a lot of smoke and debris coming down from out in front of us. It just didn't make full sense."

Before Teachout could put it together, he said, first responders had swarmed onto the bloody scene. "Rescue people were out there instantly. I don't know where they came from. There were a lot of police tending bodies that were lying on the ground. They said they want everybody off the course. They said, 'Go down this side road.' They said, 'Go to the family meeting place,' which was pre-arranged.

"We walked a couple of blocks. I was so happy to see my wife Mary waiting for me under the letter T," he said, referring to his wife, Superior Court Judge Mary Miles Teachout. Peter Teachout ran his first Boston Marathon in 1968 and more than he can remember since then. But he hadn't run the race in more than 20 years. He decided to run this year because he's teaching as a visiting professor at Boston College law school. "That's about three blocks from the Boston Marathon course," he said. "I just went out to finish."

The Burlington Free Press reported that Nancy L. Elwess of North Hero was 20 to 30 feet from the finish line when the first bomb went off; she was blown sideways and sustained cuts from glass. Elwess, a professor at SUNY Plattsburgh, treated herself, the paper reported.

Other first-hand accounts from Vermonters are still coming in.

Jason Wulff, 34, lives in Waterbury and works for a subsidiary of National Life. He finished the marathon around 1 p.m., and said he was back at the Mandarin Oriental Boston on Bolyston — about a block and a half from the marathon finish line — when the first explosion went off.

From the window of the hotel Wulff, fellow Vermonter Tim Shea and their partners watched as people on the streets below ran from the bomb sites. Wulff said the commotion died down shortly after the explosions, but that a half hour later, the atmosphere was tense and nervous. Around that time, they were evacuated from the hotel because of a reported suspicious package. 

Wulff and his wife ended up walking six miles through the city to a cousin's home in Brighton, where they camped out last night. Their car and belongings are still stranded at the evacuated hotel. 

"It's a shame, clearly," said Wulff of the bombings. "It's sad to see it happen." But in his first experience running the Boston Marathon, Wulff had positive things to say about the city, the race and the supporters who turned out to cheer on the marathoners. "It was a beautiful day for running a race."  

Jim Pugh, 62, who lives in Cornwall, said he finished the race about 50 minutes before the bombs went off.

"I was in a tavern a dozen blocks away — changing into street clothes — when the tragedy occurred," he wrote in an email. "This is where members of my former North Shore running club gather each year after the marathon. I learned about it from the TV monitors on the wall. My running friends are all safe and have found their way to the watering hole. Some of them were still running the course when the bombs went off. One was a couple of blocks from the finish when runners were told to stop. A couple were a mile short of the finish when they were stopped."

Three hours after the explosions, Pugh wrote that police cars were zipping by with "lights and sirens ablaze."

"Everyone seems to be on their cellphone, reassuring family and friends I am sure," he wrote, adding, "It was a terrific day to run. The crowds lining the course were as enthusiastic and supportive as ever."

Tim Noonan, 56, estimates he finished the marathon 15 or 20 minutes before the bombs went off. He was about a quarter-mile away at that point, and he and nearby runners turned around when they heard the first explosion — which was followed quickly by a second.

"We had no idea what happened," said Noonan, who called Seven Days while en route back to Vermont. He said race officials mobilized quickly, cordoned off the area and "shut the whole area down." 

"It's just horrible," he said. "Who would expect something like this at a marathon?"