Members of the Caballeros Templarios drug cartel burned down a pharmacy in the western Mexican state of Michoacan on Wednesday despite the presence of thousands of troops and Federal Police.

The attackers arrived just after 7:00 a.m. and ushered the employees out of the building before dousing it with gasoline and setting it ablaze, authorities said.

The pharmacy is just two blocks from the city hall in Apatzingan, hub of an area regarded as the bastion of the Caballeros Templarios (Knights Templar), where the entire municipal police force was relieved on Tuesday in favor of federal cops.

The Mexican government is mounting a major operation to reassert control in the Tierra Caliente region, which straddles Michoacan, Guerrero and Mexico states.

That region has seen clashes between the Caballeros and militias that arose to defend their communities from the cartel.

So far, however, the federal forces have confronted only the self-defense groups.

Attorney General Jesus Murillo acknowledged Tuesday that a clash occurred between vigilantes and the soldiers trying to disarm them, but he did not provide any casualty figures.

The government is trying "to restore order with the least violence possible," he told Televisa.

"There is no doubt that we have to restore the rule of law" in Michoacan, Murillo said, adding that the government was acting with "all the prudence, caution and care to prevent violence."

Estanislao Beltran, a spokesman for one of the vigilante groups in Michoacan, told Efe Tuesday that soldiers opened fire on civilians in the town of Antunez, killing four people, including an 11-year-old girl.

Following Wednesday's arson attack, Beltran questioned the ability of federal forces to provide security.

The Caballeros were able to enter Apatzingan and burn down the pharmacy even though the city is practically under siege" by the military and Federal Police, he told MVS radio.

The militia members believe the Caballeros have allies inside law enforcement and the military, Beltran said.

Self-defense groups are refusing to hand over their guns because doing so would leave them and their communities "at the mercy of organized crime," he said.

Community self-defense groups and community police forces have been formed in 15 of Michoacan's 113 municipalities. EFE