A spasm of bloodletting by organized crime groups claimed at least 40 lives over a long weekend in Mexico including a high school party where at least 18 young people were brutally slain.
In Ciudad Juarez, Mexico's murder capital, gunmen drove up to a house where a high school party was in full swing and opened fire killing at least 18, the city public safety agency said.
Most of the victims were "youngsters," said the Chihuahua state attorney general's office.
Witnesses said gunmen drove up to the house in several cars, first shooting at people gathered outside the dwelling, then chasing and cornering some of the youngsters who jumped over a fence frantically running for their lives.
The gunmen, it turned out, were looking for someone who was not even at the party, said Enrique Torres, a military spokesman. The youths were celebrating a birthday and a local soccer team championship.
Almost at the same time but in Torreon, in the northern state of Coahuila, 10 people were killed when gunmen rolled up in a trio of Hummers and opened fire on the crowd inside a bar.
Early Monday gunmen again opened fire in Ciudad Juarez at a bar, killing five people, police said, while six more were injured.
Meanwhile a clash between two organized crime groups in Madgalena, Sonora state, left seven people dead early Monday.
The war waged by several powerful drug cartels in Mexico has already left 15,000 people dead. The government has deployed 50,000 troops and thousands of police in an effort to rein in the violence.
The Juarez cartel led by Vicente Carrillo and Sinaloa cartel led by Joaquin 'Chapo' Guzman are battling for control in Chihuahua state, trying to mark their territory, authorities say, with no regard for human life.
They often act openly and boldly, knowing that corruption protects them, said former prosecutor and safety consultant Samuel Gonzalez.