Eight people have been gunned down by suspected drug gang hitmen in two incidents on the outskirts of Mexico City,
Armed men opened fire from a vehicle on a crowd of people in a street on Sunday morning, killing seven.
An hour later, police found a woman's naked body dumped on the side of a road - an apparent gunshot victim.
Despite its high crime rates and reputation for kidnappings, Mexico City has been seen as somewhat of a safe haven for small businesses fleeing even worse drug violence raging elsewhere in the country, especially near the US border.
The latest killings come one day after armed men opened fire and hurled a grenade into a crowded nightclub in the city of Guadalajara, killing six people and wounding at least 37.
It was the second grenade attack on a Guadalajara bar in less than a month, following an argument between gunmen and musicians on January 16 which ended in a blast that killed two people.
The latest attack in Guadalajara took place just hours after a shootout between soldiers and presumed cartel gunmen left eight people, including an innocent driver, dead in the northeastern city of Monterrey.
Monterrey is at the intersection of several highways - often used as drug smuggling routes - heading north into the US.
Two rival drug organisations, the Gulf cartel and their former allies, the Zetas, are battling for control of the area.
The incidents in Monterrey and Guadalajara brought the overall death toll of this weekend's drug-related violence to at least 38.
In Chihuahua state, 11 people were killed in several separate murders in Ciudad Juarez, Mexico's deadliest city, across from the US city of El Paso, Texas between late Friday and Saturday, authorities said.
Gunmen also shot dead five men together in an additional group killing on a highway between Chihuahua city, the state capital, and Ciudad Juarez, police said.
Separately, a special unit of soldiers and police known as the Immediate Reaction Group stopped two suspicious vehicles in a suburb of the industrial city of Monterrey, the secretariat of defence said.
The car's occupants responded by pulling out weapons and opening fire.
"Seven alleged aggressors lost their lives" in the shootout, the secretariat said in a statement, adding that the attackers "struck the side of a vehicle, resulting in a civilian death".
More than 34,600 people have died in drug trafficking related violence since December 2006, when the government of Felipe Calderon, the president, deployed soldiers and federal police in a widespread crackdown on the illegal cartels.