MEXICO CITY — The bound and gagged bodies of seven people have been found in a shallow grave in the violence-plagued state where President Felipe Calderon kicked off his crackdown on drug trafficking, state officials said yesterday.An anonymous call sent police to an abandoned warehouse Thursday in the Michoacan state city of Uruapan, about 180 miles west of Mexico City. There, officials removed a loose section of flooring and discovered the mass grave, said Magdalena Guzman, a spokeswoman for the state prosecutors’ office.

Officials found the bodies of three men and one woman late Thursday. Their feet and hands were tied together, and their mouths were covered with tape. Three other bodies were uncovered yesterday. All were in advanced stages of decomposition, indicating the victims were killed some time ago.

Guzman said officials were still working at the site and more bodies could be found. No suspects were in custody.

Last month, Calderon sent 7,000 troops to his native state of Michoacan. Uruapan itself has been the site of some of the most brutal slayings in Mexico, including a September 6 attack in which gunmen dumped five severed human heads onto a bar dance floor.

Drug gangs are blamed for more than 2,000 murders nationwide in 2006 and have left a particularly bloody trail in Michoacan and in the northern border city of Tijuana, where more than 300 people were slain last year.

Tijuana police stayed off of patrols on Friday after soldiers sent by Calderon to crack down on drug gangs and corruption there seized most of their guns for inspection.

Tijuana Public Safety Secretary Luis Javier Algorri said that without arms it was too dangerous for the force of 2,000 police to patrol the streets of the city where 13 officers were shot dead last year.

“This is an unfortunate situation because it leaves agents defenceless and does not allow them to serve the community,” Algorri said in a news conference.

Calderon sent 3,300 soldiers and federal police into Tijuana on Tuesday to hunt down drug gangs. The soldiers swept police stations and took officers’ guns for inspection on Thursday amid allegations by federal investigators that a corrupt network of officers supports smugglers who traffic drugs into the United States.

Opposition politicians and residents have expressed doubt that Calderon’s highly publicised campaign will have much of an impact. Calderon took office on December 1 promising to crack down on drug gangs and other organised crime.

His predecessor, Vicente Fox, also designated thousand of agents to fight drug trafficking, arresting several alleged kingpins during his six-year term. But those actions appeared to spark more violence as other traffickers battled to take over the smuggling routes of those killed or detained.