Headless bodies dumped outside school in Mexico

Drug hit men are suspected of dumping six headless bodies outside a school in northern Mexico on Monday, the latest macabre incident in a series that is putting pressure on Mexican President Felipe Calderon to act.

The bloodied, beheaded men were left outside the secondary school in the colonial city of Durango just before dawn, hours before students were due to put on a show to celebrate Mother's Day, Reuters reported, quoting the Durango state attorney general's office.

Threatening messages were spray painted on a nearby wall, but were quickly covered over by the authorities, who declined to reveal what they said.

Durango, once a quiet farming and tourist city but also a lucrative drug smuggling route to the U.S., is caught up in a war between the feared Zetas gang and the Sinaloa cartel.

Soldiers unearthed 21 more bodies — 10 men and 11 women — from mass graves in northern Mexico over the weekend, bringing the toll from a monthlong search to at least 183, the Associated Press reports.

Eleven of the bodies were found in a shallow grave in the back of a city mechanic's garage, the fourth mass grave to be found in Durango since early April. The graves are believed to hold the remains of drug cartel victims, possibly executed rivals.

Turf battles between drug cartels have claimed the lives of more than 34,600 people in Mexico in the past four years, the AP reports.

Calderon says the violence is a sign that the cartels are weakened and desperate. But that didn't stop tens of thousands of people marching through Mexico City Sunday, calling for an end to the bloodshed.