Mexican marines have found 72 bodies at a remote ranch near the United States border, after a shoot-out with suspected drug cartel gunmen.
Three gunmen and one marine were killed in the shootout.
A man with a gunshot wound led the marines to the area in Tamaulipas state, after calling for help at a navy checkpoint.
Tamaulipas has become one of Mexico's bloodiest drug flashpoints as rival groups fight over smuggling routes into the United States.
More than 28,000 people have died in drug violence since President Felipe Calderon launched a drug fight when he took office in 2006.
In recent months, an increasing number of mass graves have been discovered.