The anticipated surge of triumph at the Boston Marathon finish line Monday afternoon instantly dissolved into terror and chaos as two bombs exploded within moments of each other, killing three people, including an 8-year-old boy, and leaving at least 140 people injured, many critically.

According to news reports, law enforcement authorities are interviewing a 20-year-old Saudi national, in the United States on a student visa, identified as a "person of interest." However, they have not named the man as a suspect. Police also searched an apartment in Revere, Mass., just north of Boston, carrying out bags of items.

The first bomb, hidden in a trash barrel just short of the finish line on Boylston Street, exploded at 2:50 p.m. The second, about 1,500 feet away on the same street, went off about 10 seconds later. There are conflicting reports of two other, undetonated devices having been found.

Among those at the marathon was Lisa Georgis, 44, of New Ringgold. Georgis had finished the marathon when the bombs exploded, and was a couple of blocks away.

"I was done about 35 minutes before it happened. I was in the family meeting area, waiting for my family, when I heard the booms," she said in a telephone interview early Tuesday.

"I really had no idea what had occurred until my family found me and told me what had happened," she said.

The first blast, she said, sounded like part of the celebration.

"It sounded so calculated. I thought it was a firework or something, like it was planned. But when the second went off, I realized something wasn't right," she said.

Georgis said she saw police cars and ambulances, but did not see any smoke from where she was.

"It was bedlam trying to get out of there," she said.

Four of Georgis' children, and her stepfather, Stephen Miller, were at the race with her.

"Fortunately, my kids were nowhere near the finish line. I'm very, very blessed today that my kids are fine and that I'm fine," she said. "My kids are 16, 15, and I have 13-year old twins. My 20-year old was panicking at home."

Her cell phone was back at the hotel.

"My mother (Susan Miller) was beside herself. But now she's got us all back in the house, so she's good," Georgis said.

Despite the events, Georgis, a "passionate runner" who finished the marathon at 3.49, intends to return. She said she feels bad for those who did not get to finish the race.

"It was an unbelievable event, and I'm sure security next year will be doubled," she said.

Tamaqua Area High School 2007 graduate Lauren Davis lives about three miles from the blast site. She had gone down to see the marathon, and was walking around, cheering on the runners, and standing within a mile of the blasts.

"I just had just walked in to Boston. I was on Massachusetts Avenue when I heard two explosions," she said in a telephone interview early Tuesday. "I thought it was a bus crash. In less than 10 seconds, there were cops on bikes, in cars and on foot, all running to the scene."

Davis, an administrative assistant in the technology licensing office at Massachusetts Institute of Technology, said she had planned to meet up with some friends. But then, she said, she saw that authorities had stopped the race just before an overpass on Massachusetts Avenue.

"I knew something was going on, but didn't know what," she said.

She was unable to access the Internet, and cell service was bad. One of her friends texted her, and said she heard there were two bombs.

Davis said she began walking, trying to find out what had happened. She offered her phone to runners, including one who "didn't speak much English."

She said the runners tags had emergency contact numbers, but cell phone calls were not going through. She stopped to help a woman with three children whose mother was running in the marathon. The woman wanted to call the children's mother to tell her they were all right. However, the calls did not go through.

"When you see people running around, looking for their loved ones, you do whatever you can do to help," Davis said.