The area beyond the finish line of the Boston Marathon grew “eerily quiet” after two explosions went off, killing three and injuring dozens of others, an eyewitness said.

“I estimate that I was about half a mile away,” said Hannah Amoroso, of Baton Rouge. “I could hear them very clearly.”

Runners in the chute walking through after finishing the race looked at each other, “wanting to know what it could have been,” she said.

Amoroso said she finished the race well before the explosions went off, but waited near the finish line for a friend to finish.

“Everybody kept asking everybody if they knew anything,” Amoroso said.

It was difficult to tell where the sound had come from, Amoroso said, and she did not see any smoke.

It wasn’t until about 15 minutes later that Amoroso learned it had been an explosion.

“It was surreal,” she said. “We were crossing paths with some who had seen it.”

Amoroso, who was running in her first Boston Marathon, and her friends went to join other runners from the Varsity Sports running team at a restaurant, she said.

“We went from being really happy and talking about our race experience with our teammates to a big cloud over it,” she said.

Adam MacDowell, a runner from Baton Rouge who finished 22nd overall, was in a hotel room less than a mile from the finish line, he said.

“We got back to the hotel room and turned on the TV,” he said. “Out the window, we can see streams and streams of police cars, ambulances and fire trucks going by … I have never witnessed anything like this before.”

Another runner with the Varsity Sports group, Matthew Manning, said he was disgusted by the events.

“I can’t believe something like this would happen,” he said. “All of our prayers go out to the injured.”

All of the Baton Rouge runners were accounted for as of late Monday afternoon, family members and friends said.

Most of the 18 from Varsity Sports running team finished before the explosions, said Jenni Peters, the store’s owner.

“Most of our runners had already finished the race,” Peters said as she monitored her cellphone and Facebook on Monday afternoon.

Peters said she had gotten a text from one of the runners alerting her to the explosions. From that point, she just tried to keep people updated via social media, she said.

One runner, Joseph T. Eichorn, finished just 5 minutes before the explosions, Peters posted to Facebook.

Peters and others at Varsity Sports were celebrating the team’s high finish — the men finished second overall and the women third — when she heard about the explosions.

“You go from jubilation to the horror that something like this could happen,” she said.

Brad Bokun, whose wife, Becky, was one of the runners on the Varsity team, said she had finished the race when the explosions happened.

“She was waiting for some other people to meet,” he said. “They heard the explosions.”

The runners didn’t know what it was, he said.

“They just kind of hung around and then they heard it was a bomb,” he said.

Bokun was in a meeting and didn’t look at his phone when the texts from his wife came in, he said. When he saw the messages, he went to a computer and saw the news, he said.

“I was just waiting for somebody to confirm that they were fine,” he said. “It was pretty scary.”

Rebecca Bokun had run the race two times previously, he said.

Another runner, Leo Verde, who is a general manager at Sullivan’s Restaurant, was safe, Sullivan’s manager Lindsey Fussell said. Verde’s fiance, who traveled with him to Boston, was also safe, she said.

Louisiana Marathon Race Director Craig Sweeney and Marketing Director Danny Bourgeois were standing near the finish line earlier in the race.

“We were there at about the 2-hour mark of the race,” Bourgeois said. The explosions happened just more than four hours into the race.

Sweeney said he and Bourgeois had gone into Marathon Sports, the store where one of the explosions went off, just hours before.

“We watched the wheelchair and elite men and women come in,” he said. “Fortunately, we decided to leave.”

Sweeney said they will review the procedures in place for the Louisiana Marathon in the wake of what happened in Boston.

“We will work with police to make sure we are doing the best things for the safety of the runners, spectators and volunteers,” he said. “I will sit down with them and say what else can we do downtown.”

Including runners, volunteers and spectators, as many as 15,000 are expected for the January race, he said.

A Metairie woman, Hilary Landry, said she planned to run the race Monday, but another race kept her and her family home and possibly out of harm’s way.

The race earlier this month for the 24th Judicial District ended with Landry in a runoff against Scott Schlegel. Because of that, Landry, a lawyer and judicial candidate, decided not to run in New England.

Landry had been tracking the finish times of local runners she knows who were participating in the marathon, and said everyone she knew had crossed the finish line before the blasts. No one she knew saw them, but several heard the explosions that killed at least two people and injured dozens of others, according to media reports.

Although friends had crossed the line, she pointed out that the finish line is “where you celebrate.’’

“I’m devastated,’’ she said. “I’m sitting here looking at my three children, and every marathon I’ve ever run, they were standing there at the finish line.”

It appeared Monday evening that of the roughly three-dozen New Orleans-area runners who registered for the race, none were injured.

Roland LeBlanc, co-owner of The Louisiana Running Co. on Canal Street, said that about eight members of his running club were at the Boston Marathon. All of them had crossed the finish line and left the area by the time the explosion happened.

Kristin Depp, with Southern Runner Sports, a Magazine Street running store, said that she and other employees watched the footage of the explosion and were saddened by it.

“We have been in contact with most of our friends and family who are in Boston, and they are all shaken but unhurt,” she said.

Though the incident happened thousands of miles away, officials in New Orleans said they were going to be more vigilant in the wake of the explosions.

“It’s too early to know the full details of what happened, but one comfort the public can take from scenes like this is the fact that emergency responders are better educated, better trained and better equipped to respond to incidents of this nature,” said Capt. Ed Holmes, a New Orleans Fire Department spokesman. “NOFD first responders have been placed on heightened awareness following this incident.”

Advocate New Orleans bureau chief Sara Pagones and reporters Danny Monteverde and Kari Dequine Harden contributed to this article.