Mexican federal forces arrested 13 suspects over a span of 24 hours as part of a crackdown on organized crime in the strife-torn western state of Michoacan, the National Security Commission said.

Federal agents detained seven gunmen traveling in two vehicles in the town of Coahuayana and seized six rifles and three handguns from them, as well as two packets containing cocaine and crystal meth.

Three other individuals suspected of working for a criminal gang in Michoacan as hit men, informants or extortionists were nabbed in the town of Uruapan, the commission said Friday, adding that other drug suspects were arrested in Apatzingan or its environs.

The Apatzingan area is a stronghold of the Caballeros Templarios (Knights Templar) drug cartel, which has terrorized Michoacan for more than a year.

While the Templarios' main business is supplying crystal meth and other synthetic drugs to the U.S. market, the group has sidelines in extortion and kidnapping for ransom.

Exasperated by the cartel's crimes and the lack of response from authorities, Michoacan residents, with financial support from local businesses, decided a year ago to form self-defense groups and take on the Templarios themselves.

The federal government grew alarmed about escalating violence in the state and deployed soldiers and police in Michoacan on Jan. 13 in an effort to restore order.

Since then, authorities have arrested scores of suspects, including Dionicio Loya Plancarte, reputed to be one of the four top leaders of the Templarios.

The federal government has also persuaded militia members to join a new army-controlled Rural Defense Corps.

Police on Thursday found the heads of four Purepecha Indians in an indigenous area of Michoacan, where investigators have been searching for clandestine graves, state prosecutors said.

Officials began the search after a hitman, identified only as "El Marino" and suspected of burying the bodies, gave a statement to investigators, Estanislao Beltran, leader of one of the vigilante groups formed to fight the Templarios, told Efe.

The suspect, who was captured following a shootout between cartel gunmen and vigilantes in the city of Los Reyes, told investigators that one of the mass graves contained the burned bodies of 19 people and the other the remains of five people killed by drug traffickers.

The Federal Police on Wednesday arrested a man suspected of disposing bodies for the Templarios.

Jesus Sanchez Huerta, known as "Chucho the dismemberer," was detained in Apatzingan. EFE