Eight officers have been killed during an ambush on a Mexican prison convoy carrying drug cartel suspects.
Officals say the gunmen failed in their bid to free the prisoners - who included senior members of the Beltran Leyva cartel - and escaped in three trucks.
The attack came as police drove nine detainees to a prison in the western state of Nayarit late on Saturday.
Among the prisoners was Beltran Leyva cartel lieutenant Jeronimo Gamez, known as "The Cousin", who was arrested in January.
Despite the attack, he and the eight other suspects were delivered to prison in the state capital, Tepic.
Drug-related killings in Mexico have left more than 7000 people dead - including hundreds of members of the security forces - since January 2008.