Police footage of the moment a El Cajon, officer was shot in the neck and collapses after responding to reports an armed man was threatening to set his home and family on fire has been released.

Despite bleeding profusely from his neck wound, the officer keeps his gun aimed in the direction of the shooter as he runs away, before falling to the ground at the side of the road. He is dragged away to safety by his partner.

Two officers were called to the suburb of El Cajon on Monday (AEST) after a man was said to be brandishing a gun and trying to set his house on fire.

The suspect was going through a divorce and neighbours feared for the safety of his wife and child, who were believed to be inside the house, according to The Los Angeles Times.

The officers exchanged fire with the suspect before he retreated inside the house which was subsequently set ablaze.

The suspect's body was later found inside the house after firefighters and a helicopter dropping water extinguished the flames.

The shot police officer, who has not been identified, is in a critical but stable condition after undergoing surgery.