Investigators worked Sunday to remove wreckage of a plane that plummeted into a western Pennsylvania home, killing both people on board and narrowly missing the homeowner.

Dan Stevens, spokesman for Westmoreland County, said Sunday that workers and the National Transportation Safety Board were on the scene and making "slow progress" in trying to extricate the fuselage.

"We are in the process of trying to separate the debris of the house and the aircraft pieces, and we'll continue to do that today and tomorrow," safety board spokesman Keith Holloway said late Sunday afternoon.

Officials are also interviewing witnesses and will review maintenance records, as well as air traffic control and radar data, Holloway said. Because of the fire that erupted after the crash, investigators had still not verified the plane's identification number, he said.

The BE58 Beech Baron took off from Arnold Palmer Regional Airport in Latrobe, Pa., at 9:08 a.m. Saturday and crashed 11 minutes later in the rural area about 90 miles northeast of Pittsburgh, the Federal Aviation Administration said.

"We heard from some witnesses that they heard the engine sputtering," but those accounts must be correlated with the statements of others, Holloway said.

Stevens said the plane was on a certification flight and went through the house and landed in the garage, where it was buried by brick and concrete rubble.

"Any identifiable pieces we will collect and we will probably take to some local hangar or facility to lay it out — not necessarily put back together, but just to see what pieces we have," Holloway said.

Autopsies were planned Sunday to verify the identities of the two men on the plane, but the coroner's office was unavailable for comment.