A security guard was shot in the back of the head Saturday while trying to break up a fight during the final quarter of a high school football game in Utica.

The gunfire erupted just after 4 p.m. in a parking lot outside Thomas R. Proctor High School, the city’s police department said.

A group of about a dozen people were brawling on the pavement when at least two shots rang out, video of the incident shows.

One of the two security guards who had tried to separate the warring groups dropped to the ground after being struck by one of the flying bullets.

He was rushed to the hospital, where he remains in critical condition.

The violent group had been turned away from the varsity game against nearby Binghamton High School by another member of the school’s law enforcement just moments before the shooting, according to Utica Police Chief Mark Williams.

The stadium is outfitted with metal detectors, but the guard turned the group away before he could have been alerted to the firearm.

“He suspected that something wasn’t right with this group and he refused to lead into the stadium,” Williams said.

Police said a lone gunman — who is still on the loose — is responsible for the violent escalation.

Officers have not yet uncovered a motive for the fisticuffs but said it may possibly be gang-related.

The Utica football shooting comes just one week after a student was killed and an adult woman injured when a shooting broke out during halftime at a Lousiana high school football game.

An 18-year-old man was arrested for allegedly pulling the trigger, though authorities did not reveal the events leading up to the deadly crime.

Last month, a 16-year-old suffered the same deadly fate when he was struck by bullets that erupted from the stands during an Oklahoma football game.

Shocking video shows the moment gunfire erupted, sending players and spectators scrambling for safety.