As Boston Marathon runners walk by, SWAT team members stand guard near the finish line in Boston Monday, April 15, 2013. Two explosions shattered the
As Boston Marathon runners walk by, SWAT team members stand guard near the finish line in Boston Monday, April 15, 2013. Two explosions shattered the euphoria of the Boston Marathon finish line on Monday, sending authorities out on the course to carry off the injured while the stragglers were rerouted away from the smoking site of the blasts. ( (AP Photo/Winslow Townson) (Winslow Townson)

BOSTON — Empty plastic water bottles, discarded banana peels, Power Bar wrappers, abandoned blankets and other remnants from almost 30,000 runners who took to the course hours earlier lined Boylston Street while police roped off several blocks around the Back Bay and Copley Square neighborhoods. 

Hours after two explosions killed three people and injured more than 100 Monday afternoon at the finish line of the Boston Marathon, thousands of runners and spectators were trying to track down loved ones that were separated.

Claire Broadway, of Perth, Australia, had finished the race and was back in her 27th-floor hotel room at The Westin Copley Place when she heard the explosion.

She still had not heard from her friend and fellow runner hours after the explosion.

"We're just waiting,' Broadway said, sitting on the floor of the Westin lobby checking her cellphone. 

About an hour later, Broadway and a group of her friends exploded in cheers when they saw their missing friend had posted on Facebook.

She'd gotten to the 25-mile marker and was holed up down the road at the Marriott Hotel in Copley.

"She's safe,' Broadway said.

Friends hugged each other and wiped away tears of joy.

Happy reunions were a common sight throughout the city Monday evening.

Many spectators and runners posted to social media to let their family and friends know they were safe.

Julia Riley said she couldn't get cellphone service and lost track of her parents and brother, a fellow runner.

The Boston University senior said she eventually bumped into her parents on the street.

"It was crazy. We were hugging and crying,' she said.

Kathy McCarthy, 54, of Agawam, Mass., was able to flash a smile of relief because she was back together with her daughter, 25-year-old Hannah Rinehart, of Wellesley, Mass. The two were waiting for a friend of Rinehart's to pick them up on Commonwealth Avenue in Kenmore Square.

McCarthy had finished the race, which was her first marathon, but soon after she heard two explosions and did not know where her daughter and husband were.

She was able to track down her daughter via phone, but for two hours she did not know where her husband was and only could see online he had not finished the race. One of her husband's siblings finally reached McCarthy to let her know her husband was safe.

"I was scared and started to get panicky when I didn't hear from him,' McCarthy said. "When I found out he was fine, I was very relieved.'

Many runners also experienced an outpouring of support from residents and visitors who offered water, food, blankets and working cellphones.

Peg Largo, of Michigan, said she had crossed the finish line just moments before the explosions. She was down Boylston Street getting water, a blanket and her medal when she heard the explosion.

Like so many others near the finish line, she started running away from the blast.

"Believe me, the last thing you want to do is run when your legs are really tight,' she said.

She said she saw a lot of people who were in shock and were crying and ambulances started rushing to the scene.

"It's not what we were planning on,' said Largo. "It's just sad to think somebody would do this. I feel bad for all the people that didn't get to finish. This is a lifelong dream.'

Many race volunteers were still in shock in the early evening.

"The first explosion sounded like a howitzer,' said Susan Matz, 67, of Natick, who was handing out medical blankets past the finish line. "The thing still sticking with me is the people who were so frantic because they could not find their family of friends.'

The day's events also meant college campuses in the Fenway area usually buzzing with outdoor barbecues and parties throughout the early afternoon and evening were subdued.

Jessica Cosman, a Boston University freshman from Grafton, said many of her friends had finished all their homework by Sunday so that they could spend all day Monday enjoying the festivities.

She watched the marathon with friends near Copley Square, but had to leave early in the afternoon to go to a doctor's appointment and planned to rejoin friends later.

"The whole city was in such a celebratory mood and I felt sad to have to leave my friends early,' she said Monday evening. "But now there is no cause for celebration.'

Follow Sarah Favot @sarahfavot and Lyle Moran on Twitter @lylemoran.