Smoke billowed up near Terminal Four from the remains of Flight JK5022, an MD-82 jet bound for Las Palmas in the Canary Islands. The 15-year-old plane shot off the runway, carrying 166 passengers and nine crew, at 2:45 pm local time (8:45 a.m. EDT), according to Spanair, and witnesses described a huge explosion.

The government said 45 people were confirmed killed, 19 seriously hurt and 35 were unhurt.

But a source at the emergency services said the death toll was nearer 150. Newspaper El Pais quoted a government official on its website saying at least 100 people had been killed.

"They are pulling out burnt corpses. The plane has been completely destroyed," said the emergency services source.

Development Minister Magdalena Alvarez said she could not give a death toll, saying only that it was "a high number".

She said the cause of the accident seemed to be "an error in takeoff". But Spanish media quoted sources as saying the plane's left engine, made by Pratt & Whitney, had caught fire.

The health service of the Madrid regional government said 26 injured had been taken to hospital, although it was unable to provide a death toll.

"The (plane's) tail has broken off from the rest of the fuselage. It's difficult to describe the scene, because it's just a mess of metal," an emergency services spokesmen told national radio.

The flight was a code-sharing operation with Lufthansa serving the Canary Islands, a popular holiday destination for tourists from throughout Europe. Lufthansa said seven passengers with Lufthansa tickets, four of them from Germany, had checked in for the flight, and a Canary Islands official said passengers included Swedes and Dutch.

Thick columns of smoke rose into the air and police blocked off both ends of the Terminal Four runway, where more than 20 ambulances and many fire engines were stationed.

"I saw how the plane broke in two and a huge explosion," said Manuel Muela, who was driving past the airport when the crash occurred, according to El Mundo.

FLAG AT HALF MAST

Police escorted tearful relatives of passengers past reporters and dozens of workers identified as psychologists and social workers arrived at the terminal.

Spanish Prime Minister Jose Luis Rodriguez Zapatero interrupted his holidays and the Spanish Olympic Committee said the Spanish flag would fly at half mast in the Olympic village in Beijing.

The flight had left late after being delayed, El Mundo said.

Spanair, a subsidiary of Scandinavian Airlines Systems (SAS), has been struggling with high fuel prices and tough competition during an economic slowdown. It has announced it was laying off 1,062 staff and cutting routes to turn the airline around after losing $81 million in the first half of the year.

Just hours before the crash, Spanair's pilots threatened to strike.

SAS has been trying to sell Spanair since last year.

The MD-82 is a medium-range single-aisle plane, popular with regional airlines. It is a member of the MD-80 family of planes made by U.S. manufacturer Boeing Co. The line of planes, seating up to 172, was originally made by McDonnell Douglas as part of its DC-9 line, entering service in the early 1980s.

American Airlines had to cancel 3,000 flights earlier this year after U.S. authorities ordered them to ground MD-80 series planes to check their wiring.

Boeing bought McDonnell Douglas in 1997, and the last of the MD-80 family rolled off its production line in 1999.

Boeing did not immediately return a call seeking comment on the crash.

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