SEATTLE -

Authorities say a natural gas explosion at a North Seattle motel critically injured a man in his 40s.

The blast Monday blew the door off a room at the Klose-In Motel in the 9300 block of Aurora Avenue North.

The Seattle Fire Department reported natural gas as the cause of the fire and said damage was estimated at $55,000. The man was transported to the burn unit at Harborview Medical Center.

The Red Cross of Western Washington was helping find temporary housing for 41 people displaced by the explosion.