GAITHERSBURG, Md. - A small, private jet slammed into a house Monday, killing a woman and her young sons in the home and three people on board the aircraft, authorities said.

The jet crashed around 10:45 a.m. in Gaithersburg, a Washington suburb, Montgomery County Fire and Rescue Chief Steve Lohr said at a news conference.

Authorities quickly said all three people on the plane had been killed, but it took hours for fire crews to sweep the home and confirm that three people were inside. They were identified as 36-year-old Marie Gemmell and her two sons, 3-year-old Cole and a 1-month-old Devon.

They were found in a second-floor bathroom. Gemmell was lying on top of her young sons in an apparent effort to shield them from the smoke and fire, police Capt. Paul Starks said. Her husband and a school-age daughter were not home and were accounted for, police said.

The fuselage of the jet crashed into the front lawn of an adjacent home, which was heavily damaged by fire, and investigators believe one of its wings, which had fuel inside, was sheared off and tore through the front of the Gemmell home, said Robert Sumwalt, a National Transportation Safety Board member.

The founder and CEO of a North Carolina clinical research organization was among those on the plane. Health Decisions of Durham, N.C., said in a news release that Dr. Michael Rosenberg was among those killed.

Rosenberg was a pilot who crashed a different plane in Gaithersburg on March 1, 2010, according a government official who wasn't authorized to speak publicly and asked not to be named. Investigators are still trying to determine whether Rosenberg was at the controls at the time of Monday's crash.