10 Killed at Mexican Drug Rehab Center

Mexican police say gunmen have shot and killed at least 10 recovering addicts at a drug rehabilitation center.

The killings happened late Sunday in Tijuana, near the U.S. border.The motive for the attack was not immediately clear.

Mexican security forces have been engaged in a brutal struggle against the country's violent drug cartels since President Felipe Calderon took office in 2006.

Nearly 30,000 people have been killed since the campaign began.

Last week, Mexican security forces seized 105 tons of marijuana in Tijuana, the largest Mexican drug bust in recent years.