Rescuers said three people were aboard the plane when it collided with the corrugated iron hangar, where 13 people were sheltering from a storm.
“Five people died and eight others were injured, two of them seriously,” said Warsaw police spokesman Sylwester Marczak, adding that the pilot was among the dead.
The plane came down in the village of Chrcynno, 47 kilometres from Warsaw, at a small airport known for parachute jump training.
The Cessna aircraft had been adapted to carry parachutists.
The local fire department posted a photo on Facebook showing the tail of the plane sticking out of the hangar.
Marczak said police were alerted shortly after 1730 GMT and would launch an investigation.
