Suspected drug cartel hitmen killed 10 police officers on a highway and 28 inmates died in a prison gun battle in Mexico's escalating war over the narcotics trade, security officials say.
In the Pacific state of Sinaloa, 28 prisoners were killed and three prison guards were injured in a gun battle between rival gangs inside a jail, the daily Universal reported.
Sinaloa is the home turf of Mexico's most wanted drug lord, Joaquin 'Shorty' Guzman.
The majority of the prisoners killed were in jail for murder or drug trafficking, the head of state police, Josefina Garcia, told a radio station.
A group of prisoners broke through a series of doors using a sledgehammer to destroy the locks and video cameras, he said.
Police spokesman Martin Gastelum said the prisoners died from gunshot wounds in the worst riot the jail has seen.
Separately, in the western state of Michoacan, gunmen used a heavy truck to block a highway and opened fire on a federal police convoy.
The information we have is that there are 10 dead and several wounded, Michoacan state public security minister Minerva Bautista told a local radio station.
The Mexican government confirmed the police deaths and said an unknown number of the assailants were killed.
Michoacan, the home state of president Felipe Calderon, has emerged as a key battleground as the cult-like La Familia cartel fights other gangs and security forces for control of the mountainous state.
At least 23,000 people, mainly traffickers and police, have been killed in drug violence in Mexico since Mr Calderon launched his army-led and US-backed crackdown on traffickers after taking office in December 2006.
The escalating violence in Mexico frightens away tourists and worries the United States, which is giving millions of dollars in anti-drug aid, equipment and training to the Mexican army and police.
Some investors have frozen funding for factories in cities on the US border, especially in Ciudad Juarez, the most deadly place in the drug war and just across from El Paso, Texas.
Last Friday was the most violent day yet of Mr Calderon's presidency with 70 drug-related killings, including the murders of 19 addicts at a rehabilitation clinic in the northern city of Chihuahua.