Police in Mexico's western state of Michoacan detained an alleged member of the Knights Templar cartel who is suspected of kidnapping children to harvest their organs, an official said Monday.

Michoacan state Public Safety Secretary Carlos Castellanos Becerra alleged that Manuel Plancarte Gaspar was part of the cartel's organ-trafficking ring. The ring would kidnap children and take them to rented homes with medical equipment where their organs were removed, Castellanos Becerra charged.

"We have several statements in open investigations that point to a network of several suspects who would identify people with certain characteristics, especially children, and kidnap them," he said.

Castellanos Becerra said the cases go back several years, but he said he couldn't give any specific details or discuss evidence because the investigation is still open.

Plancarte Gaspar, 34, was detained last week along with another suspect in a stolen car. The men also had some crystal meth, Castellanos Becerra said. He said Plancarte Gaspar is the nephew of Enrique Plancarte Solis, a top Knights Templar leader.

Hours before the announcement, a leader of one of the local vigilante groups that sprang up last year in Michoacan to challenge the cartel's control told a radio station that people in the area knew the Knights Templar gang was involved in organ trafficking because several children had been rescued in his town while being transported in a refrigerated container inside a van.

"They were inside a refrigerated box, tightly wrapped in blankets," Dr. Jose Manuel Mireles, leader of the civilian "self-defense" group in Tepalcatepec, said in a morning interview with MVS radio.

Mireles said the van carrying the children was headed to the port city of Lazaro Cardenas and ended up in Tepalcatepec after making a wrong turn.

"They were all children from the same Mexico City school," he said.

He said the children's parents had allowed them to go on an outing to the beach when they were likely kidnapped. He said the children were turned over to their parents who traveled to Tepalcatepec.

Mireles didn't say when the children were rescued and didn't answer his cellphone Monday.

Mexican authorities have said drug trafficking is no longer the top source of income for the Knights Templar, which was once a top producer of crystal meth. The officials say the cartel's main sources of income are illegal mining, illegal logging and extortion.