A female Metro bus driver was assaulted early Wednesday morning while on the job.

Authorities say a 51-year-old man was getting off a Metro bus in Hollywood on Thursday morning when he struck the driver in the face. 

The Los Angeles County Sheriff's Department's Transit Services Bureau said the alleged attacker was arrested on suspicion of felony battery of a transit employee. His name was not released.

The female driver made a designated stop on North Highland Avenue at Santa Monica Boulevard about 4:20 a.m. when the man hit her in the face before fleeing, authorities said. 

Transit services bureau Lt. Leo Bauer said investigators are still trying to determine what prompted the attack. It's unknown how many riders were on the bus at the time. 

"We don't know if he hit her once or multiple times," Bauer said. "We won't know for sure until we get interior video of the attack." 

A photo from KTLA-TV Channel 5 shows the driver clutching an ice pack and pressing it to her face. Los Angeles Fire Department paramedics assisted at the scene and took her to Cedars-Sinai Medical Center. 

Metro spokeswoman Kim Upton said the driver began working part time for the department in 2000 before becoming full time three years later. A doctor will decide when the driver is fit for work again. 

"Fortunately, her injuries weren't life-threatening, but these things are traumatic," Upton said. "We take very seriously the safety of our drivers." 

Witnesses followed the suspect, who cowered in bushes outside a nearby Jack in the Box restaurant. Deputies arrested him there. 

The alleged attacker added a suspicion of vandalism to county property charge for trying to kick out the back window of the patrol car, Bauer said. 

There have been 12 reported assaults on Metro bus drivers from 2012 to March 18 of this year, said Metro spokesman Paul Gonzales

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