A small plane clipped a downtown Anchorage office building and then slammed into a nearby commercial building early Tuesday, igniting a fire and killing at least one person aboard, authorities said.
 
There were no injuries on the ground, but it's unclear if anyone else was in the plane, Anchorage Assistant Fire Chief Alex Boyd said. The crash happened in the heart of downtown, in an area surrounded by office buildings, hotels and other businesses, before most businesses opened for the day.
 

GFX MAP ANCHORAGE ALASKA

Anchorage, Alaska, is home to roughly 300,000 people. (CBC)

The aircraft belongs to the Civil Air Patrol, a civilian auxiliary of the U.S. Air Force that is made up of volunteers who help in search and rescue missions, federal authorities said.
 
There were no sanctioned flights when the plane crashed at 6:18 a.m., said Clint Johnson, Alaska region chief for the National Transportation Safety Board.

A national Civil Air Patrol statement says the pilot was 1st Lt. Doug Demarest, who joined the patrol in 2010. The FBI says he was the person killed when the Cessna 172 clipped an office building before slamming into a commercial building Tuesday.
 
The Civil Air Patrol is a civilian auxiliary of the U.S. Air Force that is made up of volunteers who help in search and rescue missions. 
 
FBI spokeswoman Staci Feger-Pellessier says no one on the ground was hurt and there was no indication anyone else was aboard the plane. In a statement, Feger-Pellessier said the FBI does not believe the incident was a terrorist act.

'It's not good weather to be flying in'

The plane came in over the shoreline toward downtown and clipped the corner of the office building, where some state employees work. Then it crashed into the lower side of an adjacent multistory commercial building, setting it on fire.
 
Crews responded quickly and had the blaze under control, fire officials said. 
 
Kent Haina, a 747 captain for UPS, said he was taking out his garbage when he saw the plane go down at a shallow angle and disappear behind a building. He then heard a loud thud and saw a plume of black smoke.
 
Haina said the wind was howling at the time.
 
"(The engine) didn't sound like it was in trouble, but the weather was pretty windy," he said. "I said to myself, `It's not good weather to be flying in."'
 

Alaska Plane Crash

A National Transportation Safety Board investigator takes photos at the scene of an aircraft crash, Tuesday, Dec. 29, 2015, in Anchorage, Ak. A small plane clipped a downtown Anchorage office building and then slammed into a nearby commercial building early Tuesday, igniting a fire and killing at least one person aboard, authorities said. (Loren Holmes/Alaska Dispatch News/The Associated Press)

The NTSB's Johnson said the crash happened amid blustery winds but that the agency is not ruling out anything as a cause. The agency looks at pilot error, mechanical problems and weather.
 
The commercial building appeared to be unoccupied at the time of the crash, though crews were searching it to make sure, Don Tallman of the Anchorage Fire Department. Authorities cordoned off an area around the building, closing several roads.
 
The aircraft also struck a transformer, and there were some power outages in the area, fire officials said.
 
The Federal Aviation Administration and the NTSB will investigate, FAA spokesman Allen Kenitzer said. He had no additional details on the type of plane.

With files from Meagan Deuling, CBC News