At least 22 people were killed in clashes between heavily armed gang members and federal police in six towns in Mexico's western Michoacán state, the interior ministry announced.
"So far, we have two federal police killed, 20 presumed criminals shot dead and another 15 people under arrest," the ministry's National Security Council said in a statement on Tuesday.
The shootouts occurred after gang members blocked highways with buses and other vehicles in Michoacán, one of Mexico's most violent states.
In May, Mexico's government promised to keep thousands of troops in the western state until peace is restored to a region that is tormented by violent drug cartels.
Officials said some 4,000 army soldiers and marines and 1,000 federal police officers were deployed at that time.
President Enrique Pena Nieto has vowed to reduce the violence that has exploded in Mexico in the last decade.
Since he took office in December, murders have fallen slightly, according to official statistics, but violent crime is still rampant in parts of Mexico.
The Mexican government last week captured the brutal leader of the Zetas drug cartel, Miguel Angel Trevino.
Drug gangs have existed for decades in this western state, where they grow marijuana and opium poppies and produce synthetic drugs in makeshift labs before shipping them to the United States.