"First off, I want to apologize to the A's and my family," said Mortensen, who spent the night in Santa Clara County jail. "Calling my dad this morning was the hardest thing I've ever had to do. I'm deeply embarrassed for what I've done and my poor judgment. I can honestly say it will never happen again. I'm very ashamed and embarrassed. ... I'm really sorry for everything I caused."

Mortensen was arrested at about 3 a.m. by a Santa Clara County Sheriff's Department deputy who was checking a car stopped on the side of Highway 17 southbound in Los Gatos, according to Sgt. Rick Sung, a spokesman for the Santa Clara County Sheriff's Department.

The A's put out a release during Sunday's game against the Angels stating that the team was aware of the situation but will have no comment until further details are available. Mortensen, 24, was acquired from St. Louis in the Matt Holliday trade in July, and he went 2-4 with a 7.81 ERA in six starts.

After starter Esteban Loaiza's 2006 arrest for drunk driving, the A's stopped providing alcohol in both clubhouses at the Coliseum and on the team plane, citing liability issues and concern for players' welfare.

In April, Angels starter Nick Adenhart was killed by an alleged drunk driver after pitching against the A's. Mortensen's former club, the Cardinals, lost reliever Josh Hancock in 2007 when he was killed while driving under the influence.