WEST HOLLYWOOD, Calif. - Mischa Barton was arrested Thursday morning for investigation of driving under the influence of alcohol and possessing marijuana after sheriff's deputies saw her car straddling two lanes of traffic.

This photo released by the Los Angeles County Sheriff's Department shows actress Mischa Barton after she was arrested and booked Thursday, Dec. 27, 2007, in West Hollywood., Calif. [Agencies]The 21-year-old actress, who starred on Fox's teen drama "The O.C.," was driving on La Cienega Boulevard in West Hollywoodwhen she was stopped at about 2:45 a.m., authorities said.

Deputies saw her vehicle straddling the lanes and failing to signal for a turn, according to a sheriff's press statement.

"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," the statement said.

Barton was arrested for investigation of driving under the influence of alcohol, driving without a license, possessing a controlled substance and possessing marijuana, according to a statement from sheriff's Sgt. John Hocking.

She spent about seven hours in the West Hollywood jail before being released on $10,000 bail. A court hearing was scheduled for Feb. 28.

Calls to her manager and publicist weren't immediately returned.

Her arrest was first reported by the Hollyscoop.comWeb site.