Gunmen killed six members of a family and wounded a seventh in Monterrey, the capital of the northern Mexican state of Nuevo Leon, state officials said.
A group of gunmen traveling in two vehicles entered a store around noon Wednesday and opened fire on everyone inside, a Nuevo Leon Security Council spokesman said.
The unidentified victims were three minors, ages 14, 15 and 16, two adult males, ages 19 and 25, and a 20-year-old woman.
A 19-year-old man, identified as Julio Cesar Campos Vasquez, was transported by paramedics to a hospital for treatment of gunshot wounds.
State police investigators coroned off the area around the store and gathered evidence.
The gunmen abandoned one of the vehicles used in the attack, the Nuevo Leon Security Council spokesman said, adding that the vehicle had been reported stolen recently.
The Gulf and Los Zetas drug cartels have been fighting for control of Monterrey.
At least 150 people have died in drug-related violence in the northern idustrial city this year.
After several years as the armed wing of the Gulf cartel, Los Zetas, originally a band of Mexican special forces deserters, went into the drug business on their own account and now control several lucrative territories.
The war on drugs launched by former President Felipe Calderon, who was in office from 2006 to 2012, left about 70,000 people dead in Mexico, the government said.
A total of 1,104 people died in violent incidents in Mexico in January, the government said in a report earlier this month.
Of the 1,104 people who died in January in incidents linked to drug cartels and other organized crime groups, 1,068 were suspected criminals and 30 were police officers, soldiers and other public officials "who fell in the line of duty," the report said.
Mexican press tallies estimated that about 12,000 people died in violent incidents linked to organized crime groups in 2012. EFE