A military helicopter carrying officials assessing damage from a powerful earthquake crashed Friday in southern Mexico, killing 13 people and injuring 15, all of them on the ground.

The Oaxaca state prosecutor's office said in a statement that five women, four men and three children were killed at the crash site and another person died later at the hospital.

A state government official who was not authorized to be quoted by name said the chopper crashed into a group of people who had been spending the night in an open field after a powerful 7.2 magnitude earthquake hit the area. Aftershocks had caused people to flee their homes for fear they would collapse.

The Defence Department said the Blackhawk helicopter suffered the mishap when it was preparing to land on a vacant lot in the city of Jamiltepec, about 19 miles from the area of Pinotepa Nacional.