Eight police officers have been killed and one wounded in a shootout in the northwestern Mexican state of Sinaloa, dpa reported.
An official at the state attorney general's office said gunmen ambushed four police cars along a highway in the town of Navolato, the Associated Press reported on Monday.
Speaking on condition of anonymity, the official said the gunmen escaped after the incident and police found a vehicle several kilometers from the site they suspect belonged to the attackers.
Sinaloa is the home of a powerful drug cartel, the Sinaloa Cartel, which also operates out of the states of Baja California, Durango, Sonora, and Chihuahua.
They are believed to be responsible for smuggling around half a metric ton of synthetic drugs into the United States each month.
Mexican President Felipe Calderon sent about 3,000 federal police and soldiers into Sinaloa in May as part of his campaign to rein in drug lords, who have run rampant in some parts of Mexico.
Over 28,000 people have been killed in drug-related violence in Mexico since Calderon began a war with the drug cartels in 2006.