The Joint Rescue Co-ordination Centre in Victoria said the float plane came down just before 4 p.m. PT.
Four rescue boats, a helicopter and a fixed-wing aircraft raced to the scene and pulled people out of the water.
All four people on board the plane survived but one person was taken to hospital with severe burns and lacerations.
The other three were treated in Bella Bella for various head and leg injuries.
Canada's Transportation Safety Board has launched an investigation into the crash.
Google Maps: Bella Bella, B.C.