A New York City investment banker, his wife and two children and one of his business partners were killed when the small plane he was piloting  crashed on a major highway in suburban New Jersey  today.

Greenhill & Co. said two of its managing directors, Jeffrey F. Buckalew and Rakesh Chawla, died when the Socata TBM-700 crashed in Harding around 10 a.m.  It had just taken off from  New Jersey's Teterboro Airport and was en route to Georgia's Peachtree DeKalb Airport when it hit  Interstate 287, one of the region's busiest highways.

 "The firm is in deep mourning over the tragic and untimely death of two of its esteemed colleagues," chairman Robert Greenhill and CEO Scott Bok said in a statement.  "Jeff was one of the first employees of Greenhill.  He and Rakesh were extraordinary professionals."

(Credit: Joe Epstein/AP)

The plane belonged to Buckalew, who the company said was an experienced pilot.

Right before the plane went down,  what Federal Aviation Administration's Jim Peters called "a garbled transmission"  came from the cockpit.  The pilot had requested to fly at a higher altitude, a request  air traffic controllers granted.

The last conversation between the pilot and air traffic control involved icing, but it's too soon to say what caused the plane to go into an uncontrolled downward spin toward the pavement,  said Bob Gretz at the National Transportation Safety Board.  "Luckily, with 287 being a heavily traveled highway, there were no injuries on the ground," Gretz said.

Eyewitnesses said wreckage from the fiery crash spread over a half-mile.

"That's one of the things investigators will look at as we get forward," Peters said.