Authorities have released the names of two men killed in the crash of a private plane at Casa Grande Municipal Airport Wednesday.

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

The Pinal County Medical Examiner's Office identified the victims Friday as Stephen J. Stafford, 51, of Green Valley and Del V. Steinbronn, 65, of Tucson.

Authorities say Stafford was a certified flight instructor while Steinbronn was a retired private practice urologist. They say both men had many years of flight experience.

The small plane was registered to a Tucson aviation company.

The crash is being investigated by the Federal Aviation Administration and National Transportation Safety Board.