An early-morning fire Monday that badly damaged a vacant house in Butler is suspicious, fire officials say.

The blaze broke out shortly after 2:30 a.m. at 219 E. Brady St., a two-story wood frame house with an attic and basement that had no utilities connected to it, authorities said.

Butler police said they believed the home had been unoccupied for at least a year.

“Any time you have a vacant house with no utilities, it’s a suspicious fire,” said Trooper Luke Nelson, a deputy fire marshal, who planned to inspect the scene this morning as part of his investigation.

Flames had taken hold of much of the house by the time the Butler Fire Department got there. Firefighters were able to save the structure.

A damage estimate was not available and it was not immediately known if the house can be repaired. Fire Chief Nick Ban did not immediately return a phone call this morning.

Fire crews remained at the scene for at least three hours.