BOSTON (AP) -- Under heavy security that included a battery of surveillance cameras and police officers on rooftops, nearly 36,000 runners hit the streets Monday in the first Boston Marathon since last year's deadly bombing, sending a powerful message of resilience.
In what some saw as altogether fitting, an American won the men's division for the first time in more than 30 years, dominating a field that included many athletes who were prevented from completing the race last year.
"I showed up, I'm back, and I am going to finish what I didn't finish last year," said Mary Cunningham, 50, of St. Petersburg, Fla., who was stopped a mile short of the finish line by the explosions on April 15, 2013.
The two pressure-cooker bombs that went off near the end of the 26.2-mile course killed three people and wounded more than 260 in a hellish spectacle of torn limbs, smoke and broken glass.
This year, police were deployed in force along the route, with helicopters circling above and bomb-sniffing dogs checking trash cans.
A total of 35,755 athletes were registered to run, the second-largest field in its history, with many coming to show support for the city and its signature sporting event. "Boston Strong" -- the unofficial slogan adopted after the terrorist attack -- was everywhere.
"I think I'm going to start crying at the starting line, and I'm not sure I'll stop until I cross the finish line," said Katie O'Donnell, a doctor at Children's Hospital who was stopped less than a mile from the end last year.
At 2:49 p.m., the time the bombs went off, spectators observed a moment of silence at the finish line. It was followed by some of the loudest cheers of the day as people whooped, clapped and rang cowbells.
Joe Ebert, of Hampton, N.H., was cheering on his son-in-law near the spot in downtown Boston where the bombs went off. He was there last year, too.
"Just wanted to let them know that they can't beat us down. I think it makes us all stronger when something like that happens," he said.
Also among the spectators near the finish line was Jeff Bauman, who lost his legs in the bombing. It was the first time he had returned to the area since the attack.
"It feels great" to be back, he said. "I feel very safe."
Sabrina Dello Russo, 38, of South Boston, was running her first marathon for a good friend, Roseann Sdoia, who lost her right leg in the bombing.
"She is my inspiration from day one last year when I saw her in the ICU. Every run I do, she is in the back of my head, and she will be keeping me going today," Dello Russo said.
While Gov. Deval Patrick said there had been no specific threats against the race or the city, spectators at the 118th running of the world's oldest annual marathon had to go through tight checkpoints before being allowed near the starting and finish lines.
Police along the route examined backpacks, particularly outside subway station exits. And runners had to use clear plastic bags for their belongings.
More than 100 cameras were installed along the course in Boston, and race organizers said 50 or so observation points would be set up around the finish line to monitor the crowd.
Runner Scott Weisberg, 44, from Birmingham, Ala., said he had trouble sleeping the night before.
"With everything that happened last year, I can't stop worrying about it happening again. I know the chances are slim to none, but I can't help having a nervous pit in my stomach," Weisberg said.
Race organizers expanded the field from its recent cap of 27,000 to make room for more than 5,000 runners who were still on the course last year at the time of the explosions, for friends and relatives of the victims, and for those who made the case that they were "profoundly impacted" by the attack.
Kenya's Rita Jeptoo won the women's race in a course-record 2 hours, 18 minutes, 57 seconds, defending a championship from last year. She had been hoping this year for a title she could enjoy.
"It was very difficult to be happy. People were injured and children died," she had said of last year's marathon. "If I'm going to win again, I hope I can be happier and to show people, like I was supposed to last year."
American Meb Keflizighi won the men's title in 2 hours, 8 minutes, 37 seconds. Cheers rose up as word of the first American man to win in Boston since 1983 spread through the pack of runners.
Keflizighi had the names of last year's victims written in black marker on the corners of his race bib.
On Twitter, President Barack Obama congratulated Keflizighi and Shalane Flanagan, the top American finisher among the women, "for making American proud!"
"All of today's runners showed the world the meaning of #BostonStrong," Obama wrote.
Dzhokhar Tsarnaev, 20, is awaiting trial in the attack and could get the death penalty. Prosecutors said he and his older brother -- ethnic Chechens who came to the U.S. from Russia more than a decade ago -- carried out the attack in retaliation for U.S. wars in Muslim lands.
Tamerlan Tsarnaev, 26, died in a shootout with police days after the bombings.
Associated Press writers Jimmy Golen, Steve Peoples and Rik Stevens in Boston and Paige Sutherland in Wellesley contributed to this report.