A dangling live power line contacted a firefighter’s helmet on Saturday morning as Portland fire crews responded to a house fire in the Sylvan-Highland neighborhood.

The incident happened soon after firefighters arrived at a burning three-story home in the 200 block of Northwest MacLeay Boulevard around 7:30 a.m., Portland Fire & Rescue said in a statement Saturday.

Officials said no one was injured.

Shortly after they arrived, firefighters confirmed that everyone who had been inside the building had safely evacuated.

Because the fire appeared to be on the verge of spreading to a second home, firefighters called for a second alarm to bring in backup; by the time the fire had been extinguished around 8 a.m., 73 firefighters had responded to the scene, officials said.

Fire investigators have discovered that the fire started in a second-floor bedroom but have not determined a cause, officials said.

— Tatum Todd covers crime and public safety. Reach them at ttodd@oregonian.com, or 503-221-4313.