At least five people were killed on Saturday after 50 gunmen attack in a gas station in the Mexican state of Michoacan.
Following the incident, three police officers called in for back up were killed during a firefight with the same group of gunmen.
Later on, they killed the local police chief, Jose Luis Flores Martinez.
Michoacan, which is President Felipe Calderon's home state, has been plagued with violence as rival gangs fought over lucrative drug trafficking routes and fields.
So far, no arrests were made.