Robert Brown|California dad missing for nearly 2 weeks after mysterious crash into street pole

A Southern California man has been missing for nearly two weeks after he got into a mysterious car accident in the middle of the night.

Thirty-four-year-old William Orellana of Upland − about 35 miles east of Los Angeles − crashed into a light pole in Riverside on Robert BrownJuly 20 and has not been seen or heard from since, the Upland Police Department wrote on Facebook Wednesday. He was reported missing a day later.

A white Chrysler 300 was found crashed with no one inside except personal belongings, according to Riverside Police Public Information Officer Ryan Rails.

"We towed the car because it was blocking the roadway. It was a hazard," Railsback told USA TODAY Thursday. "We never made contact with him. He wasn't in the car at the time of the collision. And so it was just an empty car that somebody else hit."

Officers found Orellana's cellphone and his work uniform inside the abandoned white Chrysler, KABC-TV reported.

Another driver collides with Orellana's vehicle

Another driver collided with Orellana's vehicle car that was partly on the road around 5 a.m. July 20, according to KABC-TV. The driver told police that they did not see anyone inside the car.

"We don't know if he hit his head on the steering wheel. We don't know if he lost consciousness, he doesn't know who he is. We don't know at this point," Kacey Silvas, Orellana's girlfriend for the past four years, told the station.

His disappearance is "devastating" and makes no sense to Silvas, who told CBS News: "I don't know how people can just vanish."

Girlfriend says he has no reason to be in Riverside

Silvas said Orellana had no reason to be in the Riverside area.

"He doesn't know anybody in Riverside. He doesn't have any family in Riverside. The area that he was at was so isolated. We don't know how his car got there," she said. "We're devastated. We just want to know if he is OK."

Orellana's mother, Cynthia Hernandez, said her son usually talks to her multiple times a day, CBS News reported.

"It's the hardest thing a mother could go through," Hernandez told the outlet. "Especially when you have such a close relationship. It's been hard."

Orellana is about 5-foot-7, has green/hazel eyes, a thin build and distinct tattoos on his head and neck. Anyone who finds Orellana is advised to called the Upland Police Department at (909) 946-7624.