Arizona, Aug. 6 -- Four people were killed today when a medical transport plane crashed on Navajo Nation land in US state of Arizona, according to tribal police.

"The small aircraft was enroute to pick up a patient from a nearby hospital, when the crash occurred," Navajo Nation Police said on Facebook.

The accident took place around 12:40 p.m. near Chinle, Arizona, according to police.

"We extend our deepest condolences to their family and loved ones during this time," CNN quoted Navajo Police as saying.

The plane was a Beechcraft 300, the National Transportation Safety Board said, which crashed while landing at the Chinle Municipal Airport, in the Navajo Nation, according to the Federal Aviation Administration.

"NTSB investigators are...