A lightning strike is believed to have started a house fire in Newtown.

The fire happened Wednesday on Chestnut Hill Road in the Sandy Hook neighborhood.

Firefighters found heavy smoke inside the home and called in four additional companies to keep the fire from spreading.

Firefighters say neighbors saw a lightning strike and then saw smoke in the back of the house.

No one was home, and no firefighters were injured.

The fire is under investigation.

Sandy Hook Fire Chief Bill Halstead said, “They knocked it down probably in 10 minutes once they were on scene, they had it all knocked down, but then we had a flare up in one of the walls; it was up in the walls and we had to open up a bay all the way up to the second floor.”