A Bremerton man was transported to the hospital with smoke inhalation after a house fire Thursday morning.

Officials would not release the man’s name, citing health privacy laws.

The Bremerton Fire Department was called to the blaze at 8:55 a.m., BFD Captain Mike Six said.

All units responded, which is customary for a house fire. A unit from Navy Region Northwest Fire and Emergency Services also lent support as the blaze occurred less than a block away from Naval Base Kitsap, at 205 Naval Ave. Central Kitsap Fire and Rescue also lent assistance.

Capt. Six said that on arrival the fire appeared fairly small, but it proved difficult to put out, taking between 20-25 minutes.

“It was hidden in crevices, difficult to access,” he said.

A BFD statement said the fire required an “aggressive interior attack.”

The fire started in an upstairs unit of the house, a duplex. The residents of the lower unit escaped safely, Six said, while an upstairs resident suffered from smoke inhalation. He was taken via ambulance to Harrison Medical Center.

Six said investigators were still trying to determine how the fire began. He said the fire spread “in the walls and in the floor.”

Investigators were looking at the home’s electrical system, but the cause was still under investigation Thursday afternoon.

Gabe Stutman is a reporter with the Kitsap News Group. He can be reached at gstutman@centralkitsapreporter.com.