Fire marshal determines cause of explosion at Lake Oswego restaurant

LAKE OSWEGO, Ore. - The explosion was so powerful late Saturday night, it blew the windows out of a downtown restaurant and onto the street, according to the Lake Oswego Fire Department.

The fire marshal was unable to clearly determine what triggered the explosion and fire, but the investigators found a ceiling fan which may have contributed to the cause at the Scratch Restaurant at 149 A Avenue in downtown Lake Oswego.

Firefighters arrived at the restaurant shortly after 11:30 p.m. to find its front windows in the street and smoke coming from the building. Firefighters said a fire was burning in a room off the main area of the restaurant.

Battalion Chief David Morris said, "A smoke explosion occurs when the products found in smoke, mix with air, creating a flammable mixture. When this flammable mixture finds a ignition source it creates a explosion, similar to what happens when a cloud of gas reaches a ignition source."

They were able to get the fire under control in about 10 minutes and the damage is estimated at $50,000, firefighters said.

There was no one in the restaurant at the time of the explosion and there were no injuries.