A five-alarm fire has destroyed two popular Midtown Manhattan restaurants and injured 18 people, including 15 firefighters, early Friday morning.

The fire began at about 12:30 a.m. at Frontier Restaurant and Coffee Shop, located at 593 3rd Avenue at 39th Street in Murray Hill.

More than 200 firefighters were battling the stubborn blaze, which quickly developed into a five-alarm.

Flames shot through the one-story brick building's roof and the fire spread to neighboring Lebanese eatery Byblos Restaurant on 39th Street. Both eateries were closed at the time of the fire.

"The one building has two restaurants in it that are back-to-back. A kitchen runs through its center," said a FDNY Fire Chief Richard Tobin.

"The ceiling was starting to sag, the roof was sagging. We have a big unit on the roof that has air condition and refridgeration units that were putting pressure on," continued Fire Chief Tobin. "So in safety of the members [firefighters], we had to back them out and move to an exterior attack."

Residents in the apartments above Margarita Murphy's Grill, next to Frontier on 3rd Avenue, were evacuated.

A firefighter told PIX 11 News off-camera that extinguishing the blaze will be a "long operation." And, indeed, it took firefighters nearly eight hours to completely put out the fire.

Eighteen people were injured in the blaze. Fifteen firefighters and two EMS workers sustained minor injuries and received treatment at the scene. One civilian was also hurt but the extent of the injuiries are unknown. At least two of the injured were transported to area hospitals.

The cause of the fire is under investigation, but reports say it may have started in the kitchen.

Frontier Restuarant has been a staple in Murray Hill for over 20 years. The family-owned and operated Byblos Restaurant was established in 1990.

FDNY closed surrounding streets and morning rush hour drivers were urged to avoid the area, which is near the FDR Drive and Queen-Midtown Tunnel.

The PIX 11 News studio is located just three blocks away on 42nd Street and 3rd Avenue.