One person on each plane was killed in a plane collision on the evening of September 24 near the eastern German city of Gera.
DPA quoted a local fire department spokesman as saying that preliminary investigations found that the two victims were stunt pilots, and their planes collided in the airspace near the Gera-Loimnitz airport and then crashed.
The fire department said there were no casualties in the accident except for the two stunt pilots.
Experts from the German Federal Aviation Accident Investigation Agency arrived at the scene late at night to investigate the cause of the incident.
Police, firefighters and paramedics were called to the scene after the incident, and police are conducting a criminal investigation into the incident, the Gera Police Department said.
The city of Gera is located in Thuringia.
The Gera-Loimnitz Airport website shows that the airport is used for commercial aviation and air sports, among others.