Authorities still haven't released the names of two men killed in the fiery crash of a private plane at Casa Grande Municipal Airport on Wednesday.

The twin-engine Beechcraft Air King went down as it was landing and burst into flames north of a runway.

The small plane was registered to a Tucson company — Sauo Aero Services — which didn't return calls Thursday to The Associated Press.

The Casa Grande Dispatch reports that authorities haven't been able to confirm the identity of the plane's passenger so the victims' names haven't been released yet.

The cause of the crash remains unclear. Investigators from the Federal Aviation Administration and National Transportation Safety Board were at the crash site Thursday.