The small dual-propeller medical transport plane crashed and caught fire around 12:40 p.m. local time (1940 GMT) Tuesday near the Chinle Airport, the Navajo Police Department said in a statement posted on its official Facebook page, Xinhua reported.
The plane was en route to pick up a patient from a nearby hospital at the time of the incident, and all four individuals killed in the crash were described as non-local medical personnel, according to the police.
"These were people who dedicated their lives to saving others, and their loss is felt deeply across the Navajo Nation," said Navajo Nation President Buu Nygren in a post on social media platform X.
"This is a tragic loss to the families of those onboard and to the medical air and first responder community," the Navajo Police Department added. The cause of the crash is under investigation.
The Navajo Nation is the largest Native American reservation in the United States, extending across portions of Arizona, New Mexico and Utah.