Gunmen killed six people early Wednesday inside the El Pachangon bar in Mexico state, which surrounds the Federal District and forms part of the Mexico City metropolitan area, officials told Efe.
The victims - two women and four men - were having a celebration at the bar in the city of Nezahualcoyotl when the gunmen opened fire on them, Mexico state Attorney General's Office spokesman Felix Martinez said.
The victims have "still not been identified," the AG's office spoekesman said.
Two other people were wounded in the attack and no arrests have been made, Martinez said.
More than 50,000 people, according to official figures, have died in drug-related violence since President Felipe Calderon declared war on Mexico's powerful cartels shortly after taking office in December 2006.
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.
Most of the victims have died in incidents involving members of rival drug gangs or in attacks staged by cartel gunmen on the security forces.
Calderon said last Thursday that the number of murders committed in Mexico fell "some 7 percent in the first half of this year," compared to the same period in 2011, and a downward trend was being seen "for the first time in several years."
Deaths linked to violence between criminal organizations have fallen "close to 15 percent," Calderon told the 33rd session of the National Public Safety Council, or CNSP.
The non-governmental National Citizens Observatory on Safety, Justice and the Law, however, contends that the figures were statistically irrelevant because there were notable inconsistencies in measuring the violence. EFE