MEXICO CITY (AP) — Six policemen in western Mexico were killed Monday when a gang of gunmen attacked them in an apparent bid to free a prisoner they were transporting, authorities said.

The attack was the most serious by criminal gangs since President Andres Manuel Lopez Obrador took office Saturday, pledging to quell violence in Mexico.

The attorney general of Jalisco state, Marisela Gomez Cobo, said gunmen travelling in three vehicles attacked the state police patrol near a highway in the town of La Huerta.

She said one of the attackers was wounded and captured, and police officer was also wounded. The army and police sent in forces by helicopter to transport out the wounded.

The other attackers escaped, setting up two roadblocks with vehicles they commandeered and set on fire. Mexico's drug cartels often use such barricades to cover their escape.

The state is the home base of the Jalisco New Generation drug cartel.

At his first news conference Monday, Lopez Obrador said homicides were down in the first weekend he has been in office.

Lopez Obrador has proposed using the military as a base to create a National Guard to take on heavily armed drug cartels and other criminal gangs.

The Jalisco cartel has been willing to directly attack police and army units in the past. In 2015, cartel gunmen shot down a Mexican military helicopter, killing six soldiers.

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