MEXICO CITY—At least 13 state policemen in southwestern Mexico were killed and three others wounded Monday in an ambush by suspected members of a drug cartel, the largest such attack on security forces in several years.

The attack in Michoacán state raises pressure on Mexican President Andrés Manuel López Obrador, as his government struggles to tamp down on record murder rates across the country.

Gunmen ambushed the police near the remote town of Aguililla. Mexico’s Public Security Ministry said in a tweet it would provide state officials with all needed resources to catch the attackers and bring them to justice.

The ministry said 14 policemen were killed, while Michoacán state authorities said 13 were killed and at least three wounded.

Local media showed images of burnt-out police vehicles along the road near Aguililla, which is a hotbed of violence as rival cartels fight to control drug production and smuggling routes.