“There was one very large explosion probably maybe 100 yards from where I was standing,’’ said Gottlieb, a 44-year-old from Philadelphia. “There was no mystery as to what had just happened. Then, maybe, within two seconds later there was another explosion, it didn’t seem quite as big, but there was clearly a mushroom-type cloud.

“There was no question that some sort of bomb or something went off there.’’

Gottlieb said security immediately began to clear the finish area. “We just all turned and started heading back, away from the finish line,’’ he said.

Gottlieb’s wife, Kim, and their three children were about to walk into the Copley Plaza Hotel, where they were staying, when the explosions happened. Gottlieb’s wife and children were hustled to safety inside the hotel, which security placed on immediate lockdown, but Neil was still unaccounted for outside.

The family was tearfully reunited in the hotel lobby a short while later.

Gottlieb was at a loss to describe what kind of explosion it was.

“I don’t know what it was,’’ he said. “Part of me hopes that it was some sort of malfunction of equipment that was there, but it didn’t seem that way. It’s a scary event.’’

Gottlieb had just completed his second Boston Marathon.

“It’s a dream for a lot of people [to run Boston] and to have it end that way would be a tragedy,” he said. “Actually, for those of us standing here in the hotel, it’s a disappointing end to a spectacular day. It was seven months of training that led up to this, but that’s irrelevant.’’

Samuelson met her goal

Joan Benoit Samuelson intended to commemorate the 30th anniversary of her world-record time of 2:22:43 by finishing within 30 minutes of her winning time in 1983. Samuelson, 55, met that objective by running 2:50:29, the fastest by a woman in the 50-59 age group.

“I felt good, I felt strong,’’ Samuelson said. “I went a little bit out on a limb with that [goal] projection. I don’t know what the pace-per-mile relates to, but my fastest training mile was a 7:08 pace, so I think I was well below that.”

“It’s nice to know that I can come back 30 years later and run in the wake of these fine women,’’ Samuelson added, flanked on the dais by winner Rita Jeptoo (2:26:25) and top American finishers Shalane Flanagan (2:07:08, fourth) and Kara Goucher (2:28:11, sixth).

“No matter what our age, I think we inspire each other in the sport,’’ Samuelson said.

Speaking of Flanagan and Goucher, Samuelson said “They have each other as friends and as training partners, and I think they can take our sport in this country to the next level and can compete with the best in the world.

“I know Shalane had a lot of pressure on her shoulders coming home to Boston and I think she handled the pressure extremely well and ran a very competitive race. And I know she will be back and Kara is going to be right with her.’’

Hartmann fourth again

Jason Hartmann, 32, of Boulder, Colo., had the best finish by an American, a fourth-place effort in 2:12:12.

Hartmann went out early in a lead group despite developing a blister on his left foot that nagged him from Mile 6 to the finish. He also finished fourth last year.

“Yeah, it was painful and stuff, but it really started hurting once I crossed the line,’’ said Hartmann. “But you’re just kind of running on adrenaline. I’m sure all these athletes can agree with me on this; the crowd support was great.

“You don’t want to quit when there’s so many people around you. That kind of allowed me to [say], `You know what? I don’t care about my foot.’ I came here to compete and I just tried to block out the pain as much as I could.’’

Hartmann said it was his approach to go out early with the lead pack, which was caught around the 10K mark.

“We got back to the lead pack, but about 19-20 miles that’s when the Kenyans and the Ethiopians opened it up,’’ Hartmann said. “I just had to assess the situation and see if I could handle that pace or should I just stay within myself and allow myself the opportunity to race the last 5 miles.