SAN DIEGO — A San Diego man who was beaten and seriously injured outside a Jason Aldean concert in Chula Vista last year has sued the concert promoters and a private security company claiming both failed to take the proper steps to ensure safety at the event.

According to a complaint filed this month in San Diego Superior Court, Zachary Zander was attacked and beaten by a group of drunken tailgaters at a festival held in a dirt lot outside the Cricket Wireless Amphitheatre, now called the Sleep Train Amphitheater.

The defendants — Live Nation Entertainment Inc. and Staff Pro Inc. — are accused of negligence based on inadequate security and negligent infliction of emotional distress.

Zander, 25, and a group of friends attended an outdoor festival on Sept. 22 before a concert by country singer Aldean. Like other attendees, they set up chairs and canopies in the area.

According to court records, a group of young men set up camp close to Zander and his friends. About 90 minutes before the concert, an argument started after one of the men threw beer at a woman in Zander’s group.

Later, two men started harassing two women from Zander’s group. He intervened and was attacked. No private security personnel was in the dirt lot area.

NBC San Diego has reported that charges have been filed against Camp Pendleton-based Marine Sgt. Raymond Sharkey, 27, who is accused in the beating. He has pleaded not guilty.

Zander suffered injuries to his face and other parts of his body. He underwent reconstructive surgery that involved installing screws and plates to hold together his “crushed cheek and jaw bones,” according to the complaint.He is seeking unspecified damages.

A representative from Staff Pro’s headquarters in Huntington Beach said he was not aware of the lawsuit and declined to comment. A call to Live Nation was not returned.