The plane’s pilot and four people sheltering in the hangar from stormy weather were killed in the afternoon crash in Chrcynno, firefighters spokesperson Monika Nowakowska-Brynda said. An additional five people were injured, two of them seriously, she said.
Chrcynno is about 45 kilometers (28 miles) northwest of Warsaw.
Firefighters and airborne ambulances took injured victims to local hospitals in the Nowy Dwor Mazowiecki area.
Rescuers were still checking the hangar for additional victims, said Katarzyna Urbanowska, another spokesperson for local firefighters.
Prosecutors and police were investigating the cause of the accident.