A shootout between a group of alleged Zetas drug cartel members and the military left 15 gang members and six marines dead Friday in northern Mexico, the Ministry of the Navy said.
The shootout in the northern state of Zacatecas began when the gunmen engaged the troops. It lasted all morning and also resulted in the arrests of 17 alleged gang members, according to the ministry.
Some 37,000 people have been killed in mainly drug-related feuds since Mexican President Felipe Calderon launched a military crackdown four years ago involving some 50,000 troops and police reinforcements that has so far failed to stem the bloody tide of violence.
The violence has been especially prevalent in northern Mexico, as cartels smuggle drugs -- mainly cocaine and marijuana -- to their biggest market, the United States.