Police detectives stand next to the charred body of a man hanging from a bridge in Monterrey. (Reuters/Josue Gonzalez)

Police say the first man was found Monday, burned and hanging from the bridge during rush hour, according to the AP. The second man was discovered early Tuesday in the river below another nearby bridge because the rope that suspended him had snapped under his weight.

The overpasses of Monterrey, a northern Mexico city near Guadalupe, have seen several gang killings this year, often carried out in daylight for the public to see.

And a new report claims that American guns are behind much of the bloodshed in Mexico, with at least 70 percent of the guns recovered by Mexican authorities in 2009 and 2010 traced back to the United States.

While Mexican President Felipe Calderon has made repeated requests for stricter gun laws, the new report “takes a strong position on [U.S.] Congress’s inaction in quelling the flow of American assault rifles,” according to the Atlantic’s opinion Web site the Atlantic Wire.

View the study, “Halting U.S. Firearms Trafficking to Mexico”, here.