A person injured in a serious crash in south Cobb County was an off-duty Atlanta police officer who fell asleep behind the wheel and crashed into a box truck, according to Channel 2 Action News.

Gabriel McElroy, an Atlanta police officer since 2007, was in surgery just before 9 a.m. Wednesday. He was listed in critical condition at a local hospital and is expected to survive, the television station reported.

The truck driver complained of pain to his side but did not have any serious injuries, police told Channel 2.

Both the sedan the officer drove and the truck were seriously damaged in the head-on crash just before 6 a.m. at the intersection of Six Flags Drive and Elsner Road in Austell.

Authorities closed off the area as they investigated the crash. Six Flags Drive was still closed at Elsner Road more than two hours after the accident.

The WSB 24-hour Traffic Center advised motorists to avoid the area east of Factory Shoals Road.