Two people were killed Tuesday when a medical helicopter crashed in Arizona near Apache Junction, located on the eastern edge of Phoenix, officials said. The AS350, owned by Air Methods, went down "in unknown circumstances" at just about 8 p.m. local time as it was returning to Globe, Ariz. when ended up crashing in the Superstition Mountains, according to NBC's Arizona affiliate KPNX-TV.

There were no patients on-board the aircraft when it crashed, and there was a third passenger on-board who survived the incident, however his/her status remains unclear, according to FOX News.

"We are deeply saddened by the news that two of our crew members were taken from us, and our hearts go out to their family and loved ones," the company said in a statement.

The three people on-board were a pilot, a flight paramedic and a flight nurse, reported CNN. Air Methods has declined to say who among the three died aboard to the plane, and hasn't identified any of the victims by name.

No other details are known about the crash, and the FAA and the NTSB are being assisted by Air Methods as the two agencies investigate the incident.