With the public absorbing images of chaos and blood-soaked sidewalks after a pair of explosions ripped through the end of the Boston Marathon on Monday, there was one very relieved 17-year-old in Glendale.

Alexa Dragojlovic said she was able to confirm that her 49-year-old mother from Glendale, Kelly Dragojlovic, had safely crossed the finished line just a half-hour before the explosions, which authorities said had left three people dead and injured more than 100.

[Updated April 16, 2013 : This post was updated to reflect a higher number of casualities.]

Dragojlovic, who was not injured, and her husband are under lockdown at a hotel near the site of the explosion, Alexa said.

“It’s definitely really scary, but I am really happy she’s safe,” Alexa said.

The race was Dragojlovic’s second marathon.

Dragojlovic, a nurse and who has participated in triathlons, ran the Chicago Marathon last year, her daughter said.

About three hours into the 117th running of the 26.2-mile race, an explosion went off at the Boylston Street finish line, witnesses said. It was followed by a second explosion just seconds later, the L.A. Times reported.

Video images showed bloody spectators looking dazed and chaos erupting as runners quickly shuffled to the side and would-be rescuers surged forward. Images of bloodied, injured bystanders spread on social media sites such as Twitter as authorities closed some areas around Boston for the investigation.

There were seven people from Glendale, and four from La Crescenta, listed as having participated in the Boston Marathon. Their conditions could not immediately be confirmed.

-- Jason Wells and Veronica Rocha, veronica.rocha@latimes.com

Follow on Google+ and on Twitter: @VeronicaRochaLA.