Gunmen in three vehicles opened automatic weapon fire in northern Mexico, killing eight people including three children, authorities said, amid a huge surge in deadly crime.
The gunmen attacked four vehicles in Guamuchil on Sunday, in Sinaloa state, killing passengers including two 17-year-old boys and a 12-year-old girl, Sinaloa state prosecutor's office said.
Five more people were injured in the dizzying hail of some 300 bullets when the gunmen hit the four cars as they waited at a stop light, local media reported.
The murders came just hours after an armed commando in Mazatlan, on the state's coast, killed a police commander and then briefly took hostages at a mall before escaping with them, and then setting them free, the prosecutor's office said.
Some 450 police officers have been killed in Mexico since the launch of a massive federal anti-drugs operation in December 2006.
President Felipe Calderon has sent some 36,000 federal troops into key areas controlled by trafficking organisation, especially into Sinaloa, one of the state most hit by drug-related violence.
Last month the US government approved a $1.6 billion, three-year package of anti-drug assistance to Mexico, Central America and the Caribbean known as the Merida Initiative, a large part of which is expected to strengthen Calderon's efforts.