U.S. officials said the crash of an American Airlines jet with 260 people aboard in a residential section of Queens, N.Y., does not appear to be a terrorist attack and that reports of an explosion before it broke apart in mid-air could mean catastrophic mechanical failure is to blame.

The crash of AA Flight 587, a widebody Airbus A300 that took off from John F. Kennedy International Airport Monday en route to the Dominican Republic, set homes on fire and sent a huge plume of smoke into the sky over the New York City borough. None of the plane's passengers, the bulk of whom were believed to be Dominicans, survived. At least six people were counted as missing and another 41 injured on the ground.

Bush administration officials said the FBI believed an explosion occurred aboard the jet, and witnesses reported hearing one and seeing an engine fall off. White House spokesman Ari Fleischer said there had been no unusual communications from the plane before the crash.

Deputy Police Commissioner Joseph Dunne said 265 bodies had been recovered, but didn't provide details of how many people might have died on the ground. He said six to nine people in the vicinity of the crash were missing.

As night fell, several hundred people working under the glare of klieg lights formed bucket brigades and separated debris into gruesome piles of luggage, plane parts and human remains. Police said 265 "relatively intact" bodies had been recovered; one victim, a man, was found clutching a baby.

Witnesses reported hearing an explosion and seeing an engine and other debris falling off the flaming jet as it came down. One eyewitness told Fox News the plane appeared to fall in two pieces.

An engine was found intact in a parking lot at a Texaco station two blocks from the crash site, where it had missed the gas pumps by no more than 6 feet; neighbors ran to the scene with garden hoses to put out the fire. Part of the second engine was found another block away, in a resident's back yard after it crashed through his kitchen and part of the plane's tail was later recovered from Jamaica Bay.

A City Still Recovering

The plane went down in the Rockaway neighborhood of Queens, which is home to many firefighters who were among the dead and the rescuers at the World Trade Center on Sept. 11. New York Mayor Rudy Giuliani said six houses were mostly destroyed, and six others sustained serious damage, adding that the plane nosedived into the neighborhood, which limited the size of the area that was affected and saved countless others from being killed or injured.

Investigators recovered the cockpit voice recorder, one of the two "black boxes" from the twin-engine jet. George Black of the National Transportation Safety Board said the quality of the recording was good, and that the co-pilot was at the controls, which was not unusual.

Marion Blakey, chairwoman of the NTSB, said an initial listen to the machine found nothing "to indicate a problem that is not associated with an accident."

The search continued for the flight data recorder.

American Airlines set up a hotline phone number — 1-800-245-0999 — for relatives of passengers and crew.

New York City, already mourning the thousands killed in the Sept. 11 terror attacks, was put on high alert, and fighter jets patrolled skies over the area for some time in the morning. All three local airports — Kennedy, La Guardia and Newark, N.J., — were briefly closed immediately after the crash. All bridges and tunnels into the city also were temporarily closed.

There were 251 passengers — including five infants sitting on their parents' laps — and nine crew members on board the plane, which took off from JFK in clear, sunny weather at 9:14 a.m. It crashed three minutes later in the Rockaway section of Queens, a waterfront neighborhood 15 miles from Manhattan.

A law enforcement source at the scene told The Associated Press that the likelihood of a mechanical problem stemmed from the fact that flames were seen shooting out of the left engine and that witnesses reported the plane had difficulty climbing and was banking to the left.

A U.S. official, speaking on condition of anonymity, said intelligence agencies, the FBI and the Federal Aviation Administration were reviewing all recent intelligence for any signs that terrorism was involved, but there was no immediate evidence pointing to an attack.

"They are comparing information to see if it provides any insight into what transpired. At this point, there's no indication of a terrorist attack, but it certainly can't be ruled out in the current environment," the official said.

Flight 587 had been scheduled to leave at 8 a.m. and arrive in Santo Domingo at 12:48 p.m. The flight left 74 minutes late because of security checks put in place after the World Trade Center attack, according to American Airlines Chairman Don Carty.

Fireballs and Screams

An eyewitness told Fox News that there appeared to have been an explosion in the air, sending debris flying all over the place before the plane crashed to the ground.

Jennifer Rivara said she was looking out a window from her home about five blocks from the scene. "I saw pieces falling out of the sky," she said. "And then I looked over to my left and I saw this huge fireball, and the next thing I know, I hear this big rumbling sound. I ran to the door and all I saw was big black smoke."

"People were screaming and running," said Janet Barasso, who wept as she recounted fleeing from her home a block from the crash site with her two sons, ages 10 and 16. "I thought we were being bombed, because I didn't see the plane."

John Maroney, 47, who lives near the scene of the crash, said a piece of the plane dropped on a gas station near his house.

"The whole house jumped," he said. "We were all out there with fire extinguishers and hoses, but we couldn't do much."

Catastrophic Failures in the Past

Jet engines have been known to break up catastrophically, throwing shrapnel through a plane. In 1979, an American Airlines DC-10 crashed on takeoff in Chicago, killing more than 270 people, after one of its engines broke loose and severed hydraulic lines along the wings.

In 1989, a United Airlines DC-10 crashed in Sioux City, Iowa, killing 112 people, after the metal hub that holds the engine's fan blades shattered and ruptured the jet's hydraulic lines.

In 1996, an engine fan hub ruptured on a Delta flight as it rolled down the runway for takeoff, sending shrapnel into the passenger cabin that killed a woman and her 12-year-old son.

Also in 1996, TWA Flight 800 left Kennedy Airport for Paris and crashed off Long Island, killing all 230 people aboard. The NTSB concluded the jet was destroyed by a fuel tank explosion, probably caused by a wiring spark.

The Associated Press contributed to this report.