Richard Engel, NBC correspondent, free after 5 days of captivity in Syria

Updated at 7:34 a.m. Eastern

LONDON NBC News said Tuesday morning that veteran foreign correspondent Richard Engel, two of his colleagues and their security guard were free after five days of captivity at the hands of unidentified assailants in Syria.

NBC said in a statement that Engel, who went missing along with his crew on Thursday, was "freed from captors in Syria after a firefight at a checkpoint on Monday, five days after they were taken prisoner." The network did not identify the others who had been abducted with Engel.

"We are pleased to report they are safely out of the country," NBC added.

NBC said in its statement that the captors "were not believed to be loyal to the Assad regime," but speaking live on NBC's morning show from Turkey, just hours after crossing into the country, Engel himself said his captors were members of the pro-Assad "Shabiha" militia.

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The Shabiha, which translates roughly to mean "thugs," are a network of civilian militants who have acted for decades as the unofficial police force of the Assad regime. They are backed, as is the Assad regime, by the Islamic militant group Hezbollah and by Iran.

"They were talking openly about their loyalty to the government," Engel said, describing his ordeal. "We were told that they wanted to exchange us for four Iranian agents and two Lebanese people... they captured us in order to carry out this exchange."

Engel said his captors were taking him and his crew to a Hezbollah stronghold inside Syria when they encountered the rebel checkpoint and became involved in the firefight.

According to NBC, two of the captors were killed in the shootout at the checkpoint manned by a Syrian rebel group, the Ahrar al-Sham brigade, an Islamic Salafist group which operates across Syria, but has its strongest presence in the northern city of Idlib.

What began as an Arab Spring uprising against the dictator Assad has descended over the last 21 months into an all-out civil war in Syria, fought largely along sectarian lines with the predominantly-Sunni Muslim rebels battling against the Assad regime and its Shiite Muslim backers in Iran and Hezbollah.

Several Western journalists have been detained by Assad's increasingly isolated regime, which has virtually banned independent reporting inside Syria. Others have been abducted and held briefly by armed militant groups fighting against Assad. The myriad rebel militias in Syria have vastly varying motivations -- ranging from nationalist, to purely jihadist.

One American journalist, freelance writer Austin Tice, remains missing after disappearing in mid-August. His parents visited Beirut, Lebanon, in November, seeking information about their son, but said they still had not learned who was holding him or what condition he was in.

The U.S. government has said Assad's regime is likely holding the 31-year-old former Marine, who had been reporting on Syria's civil war for The Washington Post, McClatchy Newspapers and others.

Engel, NBC's chief foreign correspondent, has extensive history reporting on and living in the Middle East. He was reporting on the war from inside Syria when he was captured. His work has won him numerous awards, including five News & Documentary Emmys.

According to NBC, Engel speaks and reads fluent Arabic and can comfortably transition between several Arabic dialects spoken across the Arab world.