BOSTON -- A small plane with two people on board was forced to make an emergency landing on a Massachusetts highway on Tuesday after experiencing engine failure while practicing maneuvers.

Plane Makes Highway Landing | Images

The plane landed on Interstate 495 southbound in Mansfield near Route 140 just before 11 a.m. Tuesday.

The pilot had radioed Norwood Airport that he was experiencing engine troubles shortly before making the emergency landing. State police identified the pilot as Matthew Kleindienst, 24, of Bridgewater, and the passenger as Brian Souza, 21, of Stoneham.

"He did have an engine failure or an engine reduction in power. We don't know at this point what caused it," said Richard Bunker, of the Massachusetts Aeronautics Commission.

The pilot may have been practicing stall maneuvers before the emergency landing.

"A stall is when the aircraft ceases to fly. It is a matter of aerodynamics. It has nothing to do with the engine or anything of that nature. What it does is gives you, in case you do have an engine failure, gives you an idea of what the airplane is going to do and how to get yourself out of the problem if it becomes one," Bunker said.

"We evaluated two occupants of the airplane -- a pilot and a passenger. Both of those people are now saying they are not injured. They are currently still being evaluated by our EMS personnel," Mansfield Fire Chief Jim Puleo said.

The plane, a Piper Cherokee single-engine aircraft, landed less than a mile from Mansfield airport, but police did not immediately know where the plane was headed.

In a stall maneuver, the pilot deliberately reduces the airspeed of the aircraft and then works to regain full control.

"We have a pretty good, significant fuel leak from the aircraft that has been contained with foam and sand. We are awaiting the FAA at this time," Puleo said.

Mansfield is about 25 miles southwest of Boston.

State police had removed the plane by mid-afternoon Tuesday and all lanes of the highway were reopened. The plane was brought to nearby Mansfield Airport.

The plane is registered to East Coast Aero Club out of Hanscom.