Eight people including six women died on Tuesday after assailants hurled molotov cocktails at a bar here, an official said.
Preliminary accounts indicate that at least six gunmen arrived at the Castillo del Mar tavern and began the attack, Quintana Roo state attorney general Francisco Alor Quezada said.
Six people were killed on the spot and two others died later at hospitals in Cancun.
Several powerful drug cartels are battling for control of the illicit trade in Greater Cancun, a year-round tourist destination that has higher median incomes than most of Mexico's metropolitan areas.
Since May 1, 15 bodies have been found in caves near Cancun used by gangs as clandestine cemeteries.