An ambush by gunmen against a police patrol in Mexico's northwestern state of Sinaloa killed at least 11 including seven policemen and four criminals, local authorities said on Monday.

The police officers were ambushed by gunmen in the town of Choix in the morning when conducting an operation in the region. The ambush also wounded three other policemen.

The incident came three days after Sinaloa Governor Mario Lopez Valdez announced that the state would take over security in the town of Choix.

During the first days of May, a clash between the military and criminal suspects left 21 civilians dead.

The authorities in Choix has recently urged the residents to take refuge in their homes to avoid exposing themselves to "rain" of bullets.

The Sinaloa cartel led by Joaquin Guzman Loera, alias as "El Chapo Guzman" who is considered by the United States as one of the most powerful drug lords in the world, is operating in the region.

In the last five years, more than 47,000 people were killed in drug-related violence in the country.