The horror of the Boston Marathon explosions unfolded in real time Monday as shock and fear scrolled down Twitter feeds and Facebook updates.
As friends and families tried to reach loved ones, phone companies reported networks were jammed.
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When Constance Korol, a marketer from Syosset, heard about the explosions while driving, she pulled over and called her friend who was in the race.
"I tried calling her, but then you've got that 'all circuits are busy' [recording] and you wouldn't be able to get through via phone," Korol said. "I did hear from her via text message. She said she finished the marathon and the explosion was just ahead of her."
Korol posted her friend's text message on Facebook to let other friends know she was OK. Soon her friends were clicking "like" on the update.
A Facebook page for the Greater Long Island Running Club became a clearinghouse of information to check on runners in Boston, said Sue Fitzpatrick, director of development at the club.
"People were saying, 'Have you heard from so and so?' " Fitzpatrick said. The replies would come back, "Yes I heard from Kelly and Kim and Kevin, they're all OK."
Other websites including Google and the American Red Cross stepped in to help people find each other. Shortly before 9 p.m. Monday night Google's Person Finder site reported that 4,200 people were trying to find someone or announce that they were OK.
As the mobile bandwidth jammed, phone companies told customers to avoid making cellphone calls.
"Customers are advised to use text or email to free up voice capacity for public safety officials at the scene," Verizon said in statement.
Even for those not trying to reach loved ones, social media sources like Twitter feeds from the Boston Police Department and the Boston Marathon became essential sources of information.
Early in the day, the police department was updating the runners' progress with posts such as "This must look so nice to these athletes!!! Great Job!!"
The next update was terrible and succinct: "Boston Police confirming explosion at marathon finish line with injuries."
With Patricia Kitchen