Updated

Assailants killed at least 27 people — decapitating most of the victims — in a part of northern Guatemala plagued by drug cartels, national police said Sunday.

The massacre of the 25 men and two women took place on a ranch in the town of Caserio La Bomba in Guatemala's Peten province near the Mexico border, according to National Civil Police spokesman Donald Gonzalez. Police and soldiers were conducting ongoing operations in the area on Sunday.

Gonzalez said police are investigating whether the attack is related to Saturday's killing in Peten of Haroldo Leon, the brother of alleged Guatemalan drug boss Juan Jose "Juancho" Leon.

"Juancho" Leon was killed in 2008 in an ambush that Guatemalan authorities blame on Mexico's Zetas drug cartel, which has increasingly wrested control of the drug trade beyond Mexico, at times by eliminating their competition. Ten others were killed in the 2008 attack.

The Guatemalan government in February lifted a two-month-long state of siege that it had declared in Alta Verapaz province, which neighbors Peten province, during which security forces were sent to quell drug-related violence.

The state of siege gave the army emergency powers — including permission to detain suspects without warrants — and resulted in the arrest of at least 20 suspected members of the Zetas gang.

Guatemala has become a major shipment point for drugs heading north to the United States.

The Zetas are a group of ex-soldiers who began as hit men for Mexico's Gulf drug cartel before breaking off on their own, quickly becoming one of Mexico's most violent gangs and spreading a reign of terror into Central America. They are notorious for their brutality, having pioneered the now-widespread practice of beheading rivals and officials.

The Zetas began controlling cocaine trafficking in the Alta Verapaz region in 2008 after killing "Juancho" Leon.

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Associated Press writer Lauren Villagran contributed to the report from Mexico City.