Mischa Barton was arrested For DUI - possession of illegal narcotics

Mischa Barton was arrested in West Hollywood early Thursday morning, PEOPLE reports.

Barton, 21, was pulled over at 2:46 a.m. after her vehicle was seen straddling two lanes of traffic and she failed to signal when making a turn, according to an L.A. County Sheriff Department. She was arrested for DUI and driving without a valid license.

"During Ms. Barton's detention, it was determined that she was an unlicensed driver and was driving while under the influence of an alcoholic beverage," according to police. "Ms. Barton was arrested and transported to West Hollywood Sheriff's station where the booking process was completed without incident."

Police also said she'd been arrested for possession of illegal narcotics.