Six people were killed when a twin-engine light airplane crashed into the Superstition Mountains in eastern Arizona Wednesday evening, authorities said.

Three adults and three children were aboard the Rockwell AC69 that originated from Mesa's Falcon Field, about 32 km east of state capital Phoenix. The plane turned into a fireball after it went down near the peak of the range.

The pilot had flown from Safford to Falcon Field to pick up his children, a spokesperson from the Falcon Executive Aviation flight school, to which the aircraft was registered, told local television channel KPHO.

On its return trip, the plane crashed into the ground and engulfed in a fiery mushroom of cloud, according to the official.

Multiple witnesses said the crash happened near the peak of the mountains around 6:30 p.m. local time. Live television footage from the scene showed several small fires burning in the dense forest. The ill-fated aircraft was apparently split in two.

Emergency crews were struggling through rugged terrain to reach the crash site, while helicopters were flying overhead with infrared lights searching for survivors, myFOXphoenix.com website reported.

Elias Johnson, a spokesman for the Pinal County Sheriff's Office, told The Arizona Republic newspaper that a tire from the plane found nearby was consistent with it being a twin-engine aircraft.

He also said that "multiple fatalities" were feared and it appeared the plane had disintegrated.

Allen Kinitzer of the Federal Aviation Administration (FAA) said his group and the National Transportation Safety Board were investigating the crash.