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.

These were people who dedicated their lives to saving others, and their loss is felt deeply across the Navajo Nation,” Buu Nygren, the Navajo Nation president, wrote in a statement.

The four people killed when a medical transport plane crashed near Chinle Airport on the afternoon of Aug. 5 were honored during a procession.