MEXICO CITY – Police in the western Mexican state of Jalisco have arrested four suspects in the massacre of 18 people whose bodies were found this week outside the city of Guadalajara, officials said.

Jalisco’s Public Safety Secretariat said in a statement Friday that the four detainees, who had weapons and drugs in their possession, were arrested in the municipality of Tala.

The suspects were apparently acting on the orders of Juan Carlos Antonio Mercado, alias “El Chato,” a suspected boss of the Los Zetas cartel, and are linked to abductions of people in the Tala hamlet of Ahuisculco, the secretariat said.

It added that authorities have confirmed that one of the detainees used an ATM card belonging to one of the kidnap victims to withdraw money.

Jalisco authorities on Wednesday found the remains of the 18 people in several vehicles on a road near Guadalajara, some who were beheaded and all of whom were mutilated.

Authorities said the victims were part of a wider group of people who had been abducted and were to be killed, although roughly 10 of them managed to escape from their captors.

The detainees were identified as Ramon Parada, 44; Cesar Alejandro Rodriguez, 20; Hector Manuel Lopez, 31; and Milton Eribaldo Castro, 21.

The secretariat also recalled that authorities on Tuesday arrested 25-year-old Laura Rosales, who was identified by the escaped kidnap victims as living at the home where they were being held.

Police also seized 10 AR-15 and AK-47 assault rifles, as well as four handguns and five fragmentation grenades at a home.

According to the authorities, the massacre stemmed from multi-state turf battles pitting Los Zetas – a band of special forces deserters turned outlaws – against Joaquin “El Chapo” (Shorty) Guzman’s Sinaloa mob, which operates in Jalisco via an ally, the Jalisco Nueva Generacion gang.

The cartels have stepped up their war in recent weeks and engaged in a number of shootouts, the most recent of which occurred in Nuevo Laredo – a border city in the northeastern state of Tamaulipas – that left 23 members of both criminal organizations dead.

In Jalisco, the bodies of 26 people were discovered on Nov. 24 inside three vehicles abandoned on a main thoroughfare in Guadalajara, Mexico’s second-largest city.

About 50,000 people have died in Mexico’s drug war since December 2006, when President Felipe Calderon took office and militarized the struggle against the country’s powerful cartels, sending soldiers into the streets to fight criminals.