At least two people were killed when a small aircraft crashed into a 52-floor building on Manhattan's Upper East Side on Wednesday in what appeared to be an accident, officials said.

The four-seat plane was owned by Yankees baseball pitcher Cory Lidle, sources at the New York police department said. The FAA confirmed the plane was owned by Lidle, 34. CNN said the pilot of the plane was Lidle and he was believed to have been killed.

US and New York officials said they had no reason to believe the crash, which occurred in overcast weather, was related to terrorism.

A New York police spokeswoman said the crash killed two people and possibly more.

Military fighter jets patrolled several US cities as a precaution, the North American Aerospace Defense Command said.

"NORAD fighters are airborne over numerous cities. They are airborne now as a prudent measure," said NORAD spokeswoman Kyle Combs. She did not say which cities were being patrolled, or how many, but added the fighters were sent up right after the plane crashed into the building.

On Wall Street, US stocks extended losses but quickly recovered once it became clear the crash was not an attack similar to the hijacked plane attacks of September 11, 2001.

"We have no reason to believe at this point that it is terrorist related," said New York City Police Chief Michael Collins.

Kathy Robinson, a spokeswoman for New York Presbyterian hospital said the facility had taken in one dead person and nine injured people.

The plane took off from Teterboro Airport in New Jersey, just miles from Manhattan, a Port Authority of New York and New Jersey spokesman said, adding he did not know how many people were on board.

The aircraft crashed at East 72nd St. and York Avenue, near the East River, a 1980s building housing mainly upscale residential apartments but which also has a specialized hospital on the bottom 12 floors.

Luis Gonzales, 23, was working in the building remodeling a nearby apartment and saw the crash.

"I was looking out the window and I saw the plane coming so close to us and it swerved to try and avoid the building but it hit the building," he said. "It was a small plane. We went knocking on doors to try and see if people needed to get out, but we did not get any answers."

"I am still shaking," he said.

Smoke and flames poured from the upper floors of the high-rise building and more than 100 firefighters were dispatched to the scene, reviving memories of the September 11 attacks.

"It's really bad. Flames are shooting from the building. I was on my terrace and I saw it," said witness Tressa Octave, who lives two blocks away.

The Federal Aviation Administration said preliminary information indicated the crash was a small plane.

The plane was flying by visual flight rules, meaning the pilot does not have to be in contact with air traffic controllers.

Justice Department spokeswoman Tasia Scolinos said, "The initial assessment is that it probably just was a bad accident."

The FAA said it imposed temporary flight restrictions in the area following the crash and caused some departure delays at LaGuardia Airport.