Taylor Landes was standing about 100 yards away from the finish line of the Boston Marathon Monday when she heard an explosion.

“I was about 100 yards away and was actually looking the other way and heard a big boom, which sounded like someone released a cannon, fired off a cannon,” said Landes, a third-year in international studies at Ohio State and a Boston native. “I turned and saw a cloud of smoke.”

The explosion was the first of two blasts that Boston Police have determined to be bombs that left at least three dead and more than 100 injured, according to the Boston Globe.

Landes said the second explosion was closer to where she was standing with her family, who attends the race together as a tradition and was supporting a family friend who ran in the race.

“About 10 seconds after the first explosion, two blocks closer to us … there was a blast with fire and a big cloud of smoke,” Landes said. “It smelled like fireworks. My brother-in-law who is a former Marine said, ‘That’s what a bomb smells like.'”

Landes said she and her family had “not confirmed where (their family friend) is,” as of about 4:30 p.m.

The series of blasts erupted at about 2:50 p.m., or about four hours after the start of the race.

Landes said the parts of the subway system and other forms of public transportation in Boston were closed due to the explosions.

A third explosion at John F. Kennedy Library, about a 15-minute drive from the marathon explosions, occurred more than an hour after the two marathon explosions. The JFK Library explosion, however, appears to be fire-related and not related to the two earlier explosions, according to Boston police. There were no injuries reported at the third explosion.

Two additional explosive devices were found and dismantled, according to the Associated Press.

Mike Dibartola, a fourth-year OSU medical student, and his younger brother, Alex Dibartola, a first-year OSU medical graduate student, both ran in the marathon, but were back at their hotel by the time the explosions occurred.

“It sounds like the explosion went off around 2:50 (p.m.). My brother and I finished in just a little over three and a half hours at about 1:35 or so. So we missed it by a little over an hour thankfully,” Mike Dibartola said.

The main group of marathon runners had a start time of 9 a.m. Monday.

Mike Dibartola said he will be thinking twice about running in an event like this again.

“It does (make me feel frightened to run an event like this again) especially in a big city like this,” Mike Dibartola said. “I don’t know what this was and what all the details are and if it was a terrorist attack, I mean, that’s what those people want. You don’t want them to win, you know? So I’m sure that security at events like this will be heightened… It’ll definitely make me think twice about it, that’s for sure.”

The Dibartolas were on the way to the airport to return to Columbus Monday at about 4:30 p.m., and Mike Dibartola said that they were nervous.

“We’re about to go to the airport and that’s not a place you look forward to going after something like this,” he said.

This year about 26,839 runners were entered in the race. There were 55 registered runners listed as hailing from Columbus, and 680 from Ohio.

The first Boston Marathon was held in the spring of 1897. The race has grown from 4,904 entrants in 1986, according to the Boston Athletic Association’s website.