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.

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

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.