Authorities say a mob beat, killed and burned two university students who were conducting a survey in a small town southeast of Mexico City.

Ajalpan town police chief Jose Manuel Gonzalez told Milenio television on Tuesday that police had tried to protect the students, but a mob dragged them from the jail, beat them, killed them and then burned their bodies. The town is about 170 miles from Mexico City.

Police say residents called to complain about strangers asking lots of questions on Monday. When officers brought them to the town hall, a mob formed, chanting that they be turned over. It's not clear if the crowd suspected them of a crime.

Vigilante killings occur occasionally in Mexico, and several have occurred recently in Puebla state, where Ajalpan is located.