A dozen inmates escaped from a prison in Mexico's northern state of Chihuahua after armed men rammed a vehicle through a security fence, authorities said.
The breakout occurred around 5.00 a m on Monday at the prison in Aquiles Serdan, near Chihuahua city, the state capital.
The attackers fired shots to distract the guards before using their vehicle to knock down the fence, allowing 12 inmates to escape.
One of the inmates was, however, recaptured, the state attorney general's office said.
Security was boosted inside the prison as the search continued for the 11 others.
Authorities did not say whether the prisoners were linked to drug cartels or organised crime gangs, as had been the case in previous instances where inmates fled with help from outside.
Prison breaks have become frequent amid the ongoing conflict among gangs and Mexican security forces.
At least 400 prisoners escaped across the nation in 2010, including 151 inmates who fled in December from a prison in northeastern Tamaulipas state.
Dozens of guards were arrested in connection with that incident.