Six people were killed and one was seriously wounded on Sunday when two medical choppers crashed on their way to a hospital in Flagstaff, Arizona, air officials declared. The helicopters collided near Flagstaff at around 3:45 in the afternoon (PDT), said Ian Gregor, a spokesman with the Federal Aviation Administration in Los Angeles.

Preliminary reports indicated that at least one patient was among the three people killed in a helicopter operated by Air Methods Corporation. The other four died, as well as the injury, occurred aboard a helicopter operated by Classic Helicopter of Utah, Gregor added.

A spokesman for the Flagstaff Police Dept. said two rescue workers were slightly injured in a secondary blast while one of the helicopters on the ground burst.

Boughner said the two helicopters slammed into a hillside covered with ponderosa pines, leaving a large field of scattered debris and causing a fire. The set fire to flame was approximately 10 to 15 acres, but was quickly contained.

Flagstaff lies about 75 miles south of the Grand Canyon National Park, one of the largest tourist draws in the U.S., which attracts some 5 million visitors a year. Four people died last year with a similar accident in Arizona, when two news television helicopters ran up while following a car chase in Phoenix.