The FBI says there was no threat to national security when a pilot crashed a small airplane into office buildings in the downtown area of Alaska's largest city late last year.

The Anchorage FBI office says in a release Monday that the crash was an intentional act but an isolated incident.

Both the FBI and the National Transportation Safety Board have closed their investigations into the Dec. 29 crash that killed the pilot, Doug Demarest.

The Cessna 172 he was flying clipped a building housing a law firm on Dec. 29 before slamming into another building. The wreck happened before most area businesses opened for the day. A family spokeswoman has said the death was a suicide.

The Civil Air Patrol owned the plane. The 42-year-old Demarest took it without permission from its hangar at Merrill Field, a small airport on the edge of downtown Anchorage.