No one was hurt but a house in Butler’s Island neighborhood was damaged this morning in a fire that started in an upstairs bedroom, authorities said.

Fire officials ruled a faulty box fan caused the accidental blaze at the two-and-a-half-story house at 312 Virginia Ave.

Diana Self, who has rented the house for 12 years, was mowing grass about 9:20 a.m. when she heard what she thought was a bell ringing.

“I thought it was a car alarm.” she said.

But Self realized the noise was the smoke alarm going off in the home she shares with her daughter and 12-year-old granddaughter.

She called 911.

In a matter of minutes, Butler firefighters were there. By that time, flames were shooting out the back bedroom where Self had seen the flames, and thick smoke was rolling through the roof.

Ten minutes later, the fire was out and the house saved.

The fire department estimated damage at $30,000 to the house and contents.

The Butler chapter of the American Red Cross arrived to help the family with emergency needs.

The family is staying with Self’s son, who lives in the area.