Gunmen who identified themselves as members of the Gulf drug cartel attacked a bar in Monterrey, the capital of the northern Mexican state of Nuevo Leon, and killed 10 people, a spokesman for the state security council said Tuesday.

The gunmen arrived at the Matehuala bar in downtown Monterrey around 11:00 p.m. Monday and opened fire on the people inside, Nuevo Leon Security Council spokesman Jorge Domene told Efe.

The gunmen told the bar's patrons and employees that they belonged to the Gulf cartel, one of Mexico's largest criminal organizations.

Four people were pronounced dead at the scene and four others died while being treated at a hospital in Monterrey, Mexico's largest industrial city, Domene said.

Investigators later found the bodies of two more people in the bar's air ducts, where they had apparently tried to hide, Domene said.

Four of the victims worked at the Matehuala bar, Domene said.

A July 8, 2011, attack on the Sabino Gordo bar blamed on the Gulf cartel left 20 people dead.

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.

More than 50,000 people, according to official figures, have died in drug-related violence since late 2006, while the Movement for Peace with Justice and Dignity, which was founded by human rights activist and poet Javier Sicilia, puts the death toll at 70,000. EFE