A decorated former Army Ranger from Lancaster is suing Los Angeles County, alleging deputies failed to protect him when he was attacked by other inmates in 2017 at the Men’s Central Jail, where he was taken after being arrested for an alcohol-related traffic accident.

Roland Vaughan’s Los Angeles Superior Court lawsuit alleges civil rights violations and negligence. The suit filed Tuesday seeks unspecified damages.

A representative for the Los Angeles County Sheriff’s Department did not immediately reply to a request for comment.

Vaughan was an Army Ranger in 2005-10, fought in both Iraq and Afghanistan and was nearly killed when an improvised explosive device detonated near him, the suit states. He military awards include the Purple Heart, the Army Commendation Medal, the Global War on Terrorism Service Medal and the Combat Infantry Badge, according to the complaint.

Vaughan, now 38, was arrested on Feb. 5, 2017, after an alcohol-related traffic accident with a motorcyclist in Lancaster, the suit states. He was housed in a unit of the Men’s Central Jail known as the “Veteran’s Dorm,’’ the suit states.

Three weeks later, Vaughan and a small group of other inmates from his unit were on the jail roof exercising, the suit states. Unknown to Vaughan, a riot had broken out in the unit housing gay inmates and others with classifications requiring they be separated from the general population, according to the suit.

Deputies pepper-sprayed about 100 fighting inmates and sent them to the roof, where they were put in an area separated from Vaughan and his 10 to 15 colleagues by a partition, the suit states.

Shortly after the deputies left, the inmates brought by deputies to the roof broke through the partition and attacked Vaughan and his fellow inmates, the suit states.

No deputies went to the aid of the inmates being attacked and in the following days some deputies laughed as they watched recorded video of the confrontation, the suit states.

Vaughan suffered an abrasion to his right arm that later became infected, the suit states. Despite his urgent pleas, he was not fully examined by a doctor until Oct. 9, 2017, when he was diagnosed with a bacterial infection of the tissue under the skin and told he had a 50 percent chance of survival, the suit states.

Doctors removed all of the skin to the muscle on Vaughan’s right arm and grafted skin from one of his thighs onto the wound, according to the suit.

“To this day, plaintiff suffers from permanent disfigurement of his right arm, neuropathy, pain and lack of mobility and the ability to use his right hand…,’’ the suit states.