The cause of a fire that broke out at the Days Inn by Wyndham on Route 7 Thursday night is under investigation.

It all started around 10:40 p.m., when an automatic fire alarm went off at the 34-guestroom hotel at 296 Ethan Allen Highway.

The Days Inn has a Ridgefield address, but Redding firefighters were first to respond.

While en route to the scene, dispatch informed them that smoke was coming from the hotel and had activated the sprinkler system.

A working fire was discovered in one of the rooms around 10:50 p.m., and mutual aid from Ridgefield was requested. Georgetown Volunteer Fire Department also responded.

Ridgefield sent two engines and an ambulance, said Ridgefield Fire Chief Jerry Myers.

West Redding Engine 1 stretched a single hose-line into the building and the fire was contained to the unit.

The fire was knocked down shortly after 11 p.m.

Firefighters shut off the hotel’s alarm and sprinkler systems, and started clearing the scene around 11:06 p.m.

There were no reported injuries.

The West Redding Fire Marshal’s Office is investigating the cause of the fire. Ridgefield Fire Marshal Mickey Grasso could not be reached for comment Monday morning.