Gunmen killed five young men early Sunday in Escobedo, a city in the northern Mexican state of Nuevo Leon, state officials said.
The victims, one of whom is a minor, were gunned down outside a house in the Ricardo Flores Magon district of Escobedo, which is in the Monterrey metropolitan area, the Nuevo Leon state Security Council said in a statement.
Masked gunmen drove up to the house and opened fire on the young men with AK-47 assault rifles, the council said, citing statements from eyewitnesses.
The gunmen fled the shooting scene in three SUVs, state officials said.
Nuevo Leon Attorney General's Office investigators found more than 100 bullet casings from AK-47 assault rifles at the crime scene.
The Los Zetas cartel has been battling the Gulf cartel for control of the Monterrey metropolitan area and smuggling routes into the United States.
Heriberto Lazcano Lazcano, known as "El Lazca," deserted from the Mexican army in 1999 and formed Los Zetas with three other soldiers, all members of an elite special operations unit, becoming the armed wing of the Gulf drug cartel.
After several years on the payroll of the Gulf cartel, Los Zetas, considered Mexico's most violent criminal organization, went into the drug business on their own account and now control several lucrative territories.
The wave of drug-related violence in Nuevo Leon claimed the lives of 2,003 people in 2011, official figures show. EFE