The three were family friends of the plane's owner, 45-year-old Jacek Mazurek, of Kearny. He was killed in the crash, as was the pilot, 46-year-old Wojciech G. Nykaza, of Lodi.
Police Capt. Timothy Clayton said the 6-year-old's parents were at the Monmouth Executive Airport when the plane went down, but that they did not witness the crash.
A National Transportation Safety Board investigator started work on the case Tuesday.
The crash was reported at 3:45 p.m on Monday. at Monmouth Executive Airport, about 35 miles east of Trenton, said Federal Aviation Administration spokesman Jim Peters. The weather was overcast, but no precipitation was falling.
Clayton said debris from the crash was scattered over a 200-foot stretch of snowy ground.
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.
Peters said 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. It was registered to Jack Air LLC, a Wilmington, Del., company. A telephone listing for the company was not immediately available.
Dana McNally, 39, of Wall, told the Asbury Park Press of Neptune that she witnessed the crash. McNally said it appeared the pilot was coming in for a landing and attempted to abort. But something - possibly the tail of the plane - broke off, she said. The plane veered to the right and nose-dived into a snowy field alongside a runway, McNally said.
"It hit face first," McNally said. "It just went right in (to the field) nose first."
Wayne Matichuk, 43, of Wall Township, was among a group on a sledding hill when he saw the plane coming in low.
Matichuk told The Star-Ledger of Newark that the plane did not have its landing gear down, and "it seemed like he was going side to side."
The pilot pulled up and "a piece of the plane fell off," Matichuk said. Then the right wing dipped and the plane rolled over before crashing upside-down into the ground, he said.
The plane crashed upside-down into the ground, he said.
"It was so surreal. After it happened, every one of us turned around and said, 'Did that really just happen?"' said Matichuk.
Clayton said the bodies of the three adults were found near the plane's fuselage. The bodies of the teen and child were found away from the wreckage, and they were apparently ejected from the plane as it broke up, Clayton said.
