Cobb County police are trying to figure out how a former Marine who served two tours of duty in Iraq was seriously injured after an altercation at a party, Channel 2 Action News reported.

Zach Gamble underwent emergency brain surgery at Wellstar Kennestone Hospital in Marietta and has been intensive care, fighting for his life, since the incident early Sunday morning at the Concord Crossing apartments.

Police became involved when they received a 911 call from a taxi driver to report an injured man in the parking lot.

“Apparently, she was backed into a space in that parking lot and as she pulled out, she felt something with the vehicle,” Sgt. Dana Pierce, a Cobb County police spokesman, told Channel 2. “She went a few more feet, stopped and discovered the body as she apparently ran over it or ran beside it.”

Police suspect, however, that Gamble’s most significant injuries were not caused by the taxi.

“What we do know is, he was at a party on Saturday evening into the early morning hours of Sunday morning, and at some point, there was some type of verbal altercation that took place. That was shortly before that 911 call was received,” Pierce said.

Partygoers heard something, but no one saw what happened in the darkness.

Gamble, who Channel 2 said worked at a local company and has a 7-year-old son, has been unable to tell police what happened.

In a phone interview with the AJC, Pierce said, "There was some type of verbal confrontation -- a lot of loud talking and yelling going on -- and from that point on there was a gap in time" when Gamble was injured.

Pierce asked anyone with information about the incident -- and specifically, what happened from 5 a.m. until 6 a.m. Sunday, when police received the 911 call -- to call the Cobb County police's Crimes Against Persons unit at 770-499-3945.