More than 20 bodies were found in the streets outside the western Mexican city of Morelia Wednesday, according to AFP.

State prosecutor Jesus Montejano told AFP that the 21 bodies had warning notes attached to them.

"Because society asked for it, this is going to happen to those who continue to rob houses, kidnappers and rapists," the warning notes said, according to Montejano.

Mexican authorities say some of the bodies showed signs of torture, with bodies piled together and their faces covered by tape.

The infamous drug cartel La Familia is based near Morelia in Michoacan state. Last June, the cartel beheaded 12 policemen.

On Wednesday, a screaming teenager with a gunshot wound was found dangling from a rope over a busy highway in the northern Mexican city of Monterrey. Police said another man alongside him was dead by the time rescuers arrived and a third was found dead below.

Witnesses told police that a group of gunmen descended from a vehicle and hanged the men off a bridge around 10 a.m., stopping traffic along one of the busiest routes in Mexico's third-largest city, which has been plagued by drug-gang violence.

All three of the men had been shot and tortured, and their hands were bound with duct tape, according to a Nuevo Leon state police investigator who spoke on condition of anonymity because he was not authorized to discuss the case.

The dead man, estimated to be in his early 20s, dangled in a blue shirt and plaid shorts. A cellphone was bound in his hands, a possible sign that he was considered an informant.

Police said none of the victims had been identified.

Two other men, one with a foot cut off, were hanged by their necks from a pedestrian bridge Sunday in Monterrey. Both died.

The city has seen a spike of violence since the Gulf and Zeta cartels began fighting for control of drug traffic there two years ago.

According to AFP, nearly 37,000 people have died in drug violence since the Mexican government started cracking down on cartels in 2006.

The Associated Press contributed to this report.