A cargo truck crash killed 53 migrants in southern Mexico on Thursday. Dozens more are injured, with three in critical condition, according to the office of Mexico’s attorney general. Authorities believe the people crammed inside a speeding shipping container—estimates peg the group at more than 100—were Central Americans attempting to reach the U.S. The director of the Chiapas Firefighter Institute, Marco Antonio Sanchez, said there were so many victims that first responders were forced to load the injured into pickup trucks for transport to nearby hospitals because there were not enough available ambulances. Some injured victims ran from rescuers in an apparent attempt to escape deportation, according to the Associated Press.