LOS ANGELES — A Los Angeles police officer has been charged with assault for allegedly pistol-whipping a man outside a bar while off-duty.

KCBS-TV reports (http://cbsloc.al/2foz9M3 ) 33-year-old Joseph Rooney pleaded not guilty Tuesday to four counts of assault with a firearm.

Rooney allegedly pulled a gun last year on three men who’d just left an El Segundo bar. Prosecutors say he approached, struck one man in the face with the gun and pointed it at the other two men before leaving.

There’s no word on what prompted the attack.

Rooney is a nine-year veteran of the LAPD. If convicted, he could face up to 27 years in state prison.