Southern California residents who participated in Monday's Boston Marathon described the horror and chaos that ensued when two explosions went off at the finish line, killing two people and wounding at least 100.
Complete Coverage: Boston Marathon Explosions
Nancy Jo Rettig, of Redondo Beach, was running with a group called Loopsters when she heard the explosions.
“We were walking towards the tunnel,” she said from her cellphone as she and her group walked back to a houseboat in the harbor where they were staying. “You could smell it in the air.”
She said chaos ensued as police checked their radios and began ordering people out of the area. She said transit was shut down immediately and runners were ordered out of the tunnel.
"I just crossed the finish line and heard an explosion and didn't know what it was," said Grace Kim, a runner who was in Boston with the Cerritos-based "Easy Runners" club.
"It sounded louder than fireworks," Kim said.
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As the news developed, Southern California law enforcement agencies began the process of expanding security as a precaution against the potential for a similar attack here.
Google has launched a person finder to help find people who were at the Boston Marathon or to report information on people who were there.
Southern California running groups used social media websites such as Facebook and Twitter to find and spread news about members who participated in the Boston event.
L.A. Leggers posted a Facebook message attributed to member Jennifer Hartman, who said she was 20 yards away from the finish line when the bomb went off.
"We saw it all," the post said. "We turned around and were going to go back when the explosion behind us occurred. At that point we stood in the middle for a moment holding hands and wondering if any more explosions were going to happen."
As of Monday afternoon, seven of 10 Los Angeles Running Club members who ran in marathon had been confirmed safe through social media, said Alan Culver, the club's vice president who has run the Boston Marathon twice in past years.
Culver said that judging by the unaccounted-for members' previous finish times, they probably would have finished long before the explosion occurred. One runner, however, was slowed down by an injury and finished four minutes after the explosion.
"I believe they're going to be fine," Culver said. "We're just trying to piece it together."
NBC4's Kevin LaBeach contributed to this report.
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