GAITHERSBURG, Md. — A small private jet crashed into a house Monday in suburban Washington, killing at least six people, including three in the house it hit, authorities said.

At least three people, including the founder and chief executive of a clinical research organization, were killed in an Embraer EMB-500/Phenom 100 twin-engine jet that was on approach to nearby Montgomery County Airpark, an airport for small, private planes about 20 miles north of the nation’s capital.

A stay-at-home mom and her two young children also perished, said spokesman Pete Piringer of Montgomery County Fire & Rescue Service. A 5-year-old daughter went to school Monday morning and is safe; the father of the family, Kenneth Gemmell, also was not home at the time of the crash.

The corporate jet, registered to Sage Aviation of Chapel Hill, N.C., crashed into one two-story wood-frame home, setting it and an adjacent home on fire at around 10:45 a.m. ET. A third home also was damaged.

In the plane was Dr. Michael Rosenberg and two others whose names have not been released, according to a news release from Health Decisions of Durham, N.C. The company provides services for clinical trials.

“We can best honor Michael by carrying on and realizing his vision of a more efficient approach to clinical development,” said Dr. Patrick Phillips, the private company’s vice president of clinical affairs. Succession plans will be announced later.

On the ground, Marie Gemmell, her 3-year-old and her 6-week-old were on the second floor in the most damaged of the houses, where the first floor was nearly blown out, said Chief Steve Lohr of Montgomery County Fire & Rescue.

A wing of the aircraft, which contains fuel, catapulted into that house, said Robert L. Sumwalt, a National Transportation Safety Board spokesman.

“At first … I heard a sputtering sound,” said nearby resident Jocelyn Brown, who is used to hearing planes overhead that are traveling to the airport. “After the one initial crash, boom, you heard three other explosions. People were saying they thought it was gas lines.”

Crews put out the fire, shut off the utilities and searched the house that was nearly destroyed, finding the bodies hours later, Piringer said.

Brown said Gemmell was a sweet woman who walked with her kids all the time in the area.

“I yelled, ‘Anybody in there, hello, hello? Can you hear me?’ ” Brown said. “I was really close to the house, and people were holding me back.”

Witnesses said they saw the airplane wobble and appear to struggle to maintain altitude before going into a nosedive and crashing. Radio traffic out of the airport shortly before the crash talked about nearby birds, which can be sucked into a jet’s engine and cause stalling.

“This guy, when I saw him, for a fast jet with the wheels down, I said, ‘I think he’s coming in too low,'” said Fred Pedreira, 67, who also lives nearby. “Then he was 90 degrees — sideways — and then he went belly up into the house, and it was a ball of fire. It was terrible.

“I tell you, I got goosebumps when I saw it. I said, ‘My God, those are people in that plane,” Pedreira said. “I just hope nobody was in that home.”

The plane caused the explosion and fire in one house, clipped a second house and its fuselage and other debris settled in the front yard of a third home.

Planes fly low over the neighborhood every day, said Emily Gradwohl, 22 who lives two doors down from the house that the jet hit.

“I heard like a loud crash, and the whole house just shook,” she said. That’s when she ran outside to see her neighbor’s house engulfed in flames.

Montgomery County Airpark is the fourth busiest general aviation airport in Maryland, according to its website. No one at Sage Aviation, which makes replacement parts for the aviation industry, could be reached for comment Monday.

Cockpit voice and flight data recorders have been recovered, an NTSB spokesman said. Typically, crash investigations take months to complete.

Contributing: The Associated Press

Marie Gemmell posted this 2012 photo of herself and her older son, Cole, on Facebook. Cole’s younger brother also died as a result of the plane crash.

Dr. Michael Rosenberg uses this photo on his LinkedIn profile.

Six people were killed after a small private jet crashed into a house Monday in suburban Washington, including a mom and her two children n the house it hit, authorities said.