CHINLE, Ariz. (AP) — Four people died Tuesday when a medical transport plane crashed and caught fire on the Navajo Nation in northern Arizona, the tribe said in a statement.

Four people were killed Tuesday when a medical transport plane crashed on Navajo Nation land in Arizona, according to tribal police.

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.