WILTON – The cause of a fire Sunday afternoon that destroyed Bill and Lois Fletcher’s house on Orchard Drive remained unknown Tuesday evening, fire Chief Sonny Dunham said.

A Wilton firefighter was injured and three animals perished in the blaze, while a fourth animal remains missing.

Dunham said state fire investigators and Wilton firefighters were at 894 Orchard Drive all day Monday trying to determine the cause of the fire that gutted the century-old home.

The fire started on the front left side of the house in the library and office area, Dunham said, but the cause is being investigated.

Firefighters from eight departments along with other emergency services responded to the fire, which was reported at 2:52 p.m. while the Fletchers were away from the home.

Wilton firefighter Stephen Lakin slipped on ice at the scene and hurt his back, Dunham said.

He was checked by paramedics from NorthStar Emergency Medical Services and taken by ambulance later from the fire station to Franklin Memorial Hospital in Farmington after the pain worsened, he said.

Lakin was treated and released, Dunham said.

Two cats and a dog died in the fire, he said, and an older cat is missing.

The couple has met with their insurance adjuster, Dunham said.