A small medical transport plane crashed and caught fire Tuesday on the Navajo Nation in northern Arizona, killing all four people on board, the tribe said.

A small medical transport plane crashed and caught fire Tuesday on the Navajo Nation in northern Arizona, killing four people, the tribe said in a statement.

The plane was landing at Chinle Municipal Airport in the Navajo Nation in Arizona to pick up a patient for a medical transfer. It was not immediately clear what had caused the crash.