Image credit: Bill Greene/The Boston Globe via Getty Images

After the explosions at the finish line of the Boston Marathon this afternoon that killed two people and injured at least 99, many in the area reported problems with their cellular networks, saying they had difficulty making calls.

As often happens after any catastrophic event, many attributed the problems to network congestion. But the Associated Press first reported, according to a law enforcement official, that cellphone service had been shut down in the area to "prevent any potential remote detonations of explosives."

But the Federal Communications Commission and cellular carriers told ABC News that they were not aware of any cellphone service shutdowns in Boston today. ABC News confirmed with Verizon, AT&T and Sprint that not only was there service, but the networks were attempting to strengthen signals and network coverage in Boston to handle the call and data volume.

"We have not been asked by any government agency to turn down our cell service," Tom Pica, a Verizon spokesman, told ABC News.

Sprint said something similar when reached by ABC News. "Minus some mild call blocking on our Boston network due to increased traffic, our service is operating normally," Crystal N. Davis, a Sprint spokeswoman, told ABC News.

"Sprint did augment capacity on its cell sites along the marathon route in preparation for today's race and voice levels are returning to normal as law enforcement and first responders have cleared out the area as part of their emergency response."

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Sprint and AT&T said that they were asking their customers in Boston to text rather than call to free up lines for emergency personnel.

Boston Marathon racer Jill Elaine Czarnik, 24, told ABC News that the message to text rather than call was being spread around the area by race officials and police. "They're saying just send texts and not to make phone calls so people can reach their loved ones," she said.

Hours after the explosions, President Obama addressed the nation: "We do not know who did this or why. … But make no mistake. We will get to the bottom of this," he said.