Debris was scattered across 200 feet.
The crash was reported at 3:45 p.m. at Monmouth Executive Airport, about 35 miles east of Trenton, said Federal Aviation Administration spokesman Jim Peters.
Capt. Tim Clayton said the victims were three men, a teenager and a young child. The names of the victims were not immediately released, but Clayton said at least three were related. Two were from New Jersey, the other three from elsewhere, he said.
The plane was based at the airport and was returning to land when the crash occurred, Clayton said. It was not immediately clear how long the plane was gone. Relatives of some of the victims were at the airport when the crash occurred, Clayton said, but it was not clear if they had witnessed the crash.
The plane was a Cessna 337 Skymaster, a make known in aviation circles as a "Push Me, Pull You" because its twin engines are located in the nose and behind the fuselage. Whether the plane was taking off, landing or in flight at the time of the crash was not immediately clear.
Some sledders who were in the area reportedly saw the crash and called authorities, officials said.
Eric Ross was flying a helicopter nearby told Eyewitness News what he saw.
"I was flying this helicopter here next to the crash," Eric Ross said. "I was coming down the opposite way, getting ready to land, and I looked, I had to do a double take. I see the plane coming down the runway, not landing, not taking off. Doing what we call, it looked like a high-speed low pass. And there's a hill in the middle of the field. When I saw him before the hill, he was straight level. He disappeared behind the hill from my vantage point, and then we came out the other side, the plane was just rolling all over and I saw it hit the ground, and a big explosion of snow and dirt and everything."
Dana McNally, 39, was one of the sledders. Ross said she approached him and told him what she saw.
"There was a witness, I saw a lady who was, there were kids on the other side, they were sledding on a hill," he said. "She came over and said she saw the plane doing this pass, and it looked to her like something, like a piece of the wing came off, and then it started to roll...I saw the one body laying on the taxiway there, nobody's getting out of that."
The aircraft was registered to Jack Air LLC, a Wilmington, Del., company. A telephone listing for the company was not immediately available.
The airport, formally known as Allaire Airport, is located near the Jersey shore. Monmouth County is a largely affluent area of central New Jersey that is home to many business executives, entertainers and upscale seashore communities.