ISIS claims responsibility for deadly Lebanon attack in potential game-changer

ISIS claimed responsibility for twin suicide blasts that killed dozens of people in Lebanon Thursday, an attack that could escalate Sunni-Shia violence in the Hezbollah hub.

An ISIS statement released after the bombings credited "caliphate soldiers" in southern Beirut, according to the Middle East Media Research Institute. Sunni ISIS previously had not made significant inroads into Lebanon due to Hezbollah's strength.

The attack killed at least 37 people and wounded more than 180 others, George Kittaneh, head of the Lebanese Red Cross operations, told state-run National News Agency.

It was one of Lebanon's deadliest attacks in years. The explosions hit minutes apart in an area called Burj al-Barajneh during rush hour.

According to a Lebanese security official, the first suicide attacker detonated his explosives' vest outside a Shiite Mosque, while the second blew himself up inside a nearby bakery.

An apparent third suicide attacker was found dead, his legs blown off while he still wore an intact explosives' belt, said the official, speaking on condition of anonymity in line with regulations. The official speculated the third may have been killed from the explosion of the second suicide attacker, as he was reportedly close to that blast.

The Al-Mayadeen TV also reported there was a third would-be suicide attacker, describing him as a bearded young man who wore an explosives' belt. The report said he was killed before he was able to detonate the explosives.

Hospitals in southern Beirut were calling on people to donate blood and appealed on residents not to gather at the hospital gates so that ambulanced and emergency staff could work unhindered.

Shortly after the explosions, ambulances rushed to the area and started evacuating the wounded and the dead as Lebanese troops and Hezbollah gunmen cordoned the area, preventing anyone from getting close.

"There is a massacre inside and we will not let you take photos," a Hezbollah member screamed at an Associated Press photographer at the scene.

An hour later, ambulance sirens could still be heard in Beirut streets.

Hezbollah also called on people to leave all coffee shops in the area, which are usually packed with people, and urged residents to inform the group about any suspicious moves.

Fox News' Jennifer Griffin, Matt Dean and The Associated Press contributed to this report.