SMOLENSK, Russia — Investigators scrambled on Sunday to determine if pilot error was to blame for the fiery crash of a Soviet-era airliner that killed Polish President Lech Kaczynski and 96 others.
The presidential party was en route to a memorial service for Poles massacred by Soviet troops in World War II when its Tupolev Tu-154 airliner crashed in thick fog while approaching Smolensk airport, in the west of Russia.
The disaster sent Poland into shock.
Mourners in Warsaw turned out by the tens of thousands on Saturday to sing the national anthem, wave the red and white Polish flag, and lay a carpet of candles and flowers at the presidential palace and nearby Pilsudski Square.
"It's my heart that told me to come here, I simply had to come," said 45-year-old translator Anna Ciostek, who came to the square with her daughter and mother. Scene: Candles and tears for Poland's tragic president
Polish Prime Minister Donald Tusk and the late president's twin brother, former prime minister Jaroslaw Kaczynski, visited the crash site late on Saturday evening, accompanied by Russian Prime Minister Vladimir Putin.
The remains of all the victims were recovered and transferred to Moscow in two heavy-lift military helicopters for identification, as next of kin began to arrive in the Russian capital. Scene: Plane lies mangled in 'forest of death'
"Everything must be done to establish the reasons for this tragedy in the shortest possible time," said Putin when he arrived in Smolensk, about 75 kilometres (45 miles) from the Belarus border.
Besides the 60-year-old head of state, the mid-morning crash killed his wife Maria, as well as Poland's military chief of staff, other senior officers, its central bank govenor, deputy foreign minister and members of parliament. Facts: Polish leaders killed in crash
"This kind of dramatic tragedy is unheard of in the modern world," Tusk said before heading to the crash site.
Thrust into the forefront as acting president was Bronislaw Komorowski, speaker of the Polish parliament.
"It is rare for so many high ranking representatives of the highest military and spiritual leaders, and the president himself, all to die at the same moment," he told AFP.
"We have to deal with this very difficult problem -- and we will."
The Tu-154 was preparing to land at Smolensk airport in fog when "it clipped the tops of the trees, crashed down and broke into pieces," regional governor Sergei Antufiev told Russia-24 television news network.
While investigators began their work, Lieutenant General Alexander Alyoshin, deputy head of the Russian air force, revealed that the pilots of the ill-fated airliner had repeatedly ignored instructions from air traffic controllers.
Wreckage -- including the engines and a large chunk of mud-caked tailfin -- was scattered across a forest. While sections burned for more than an hour, the black-box flight recorders were found, news agencies reported.
Some 1.5 kilometres (one mile) from the airport, air traffic controllers noticed the Tupolev -- overhauled in December 2009, according to manufacturers Aviakor -- was below its appropriate glide path, Alyoshin said. Profile: Kaczynski, from child star to Polish president
"The head of the (air traffic control) group ordered the crew to return to horizontal flight, and when the crew did not fulfil the instruction, ordered them several times to land at another airport," he said.
"Nonetheless the crew continued to descend. Unfortunately this ended tragically."
Kaczynski and his delegation were to attend a memorial service in the Katyn Forest, near Smolensk, for 22,000 Polish officers and troops killed in 1940 by Soviet troops acting on orders from Josef Stalin.
The event was intended to help reconciliation between Poland and Russia, two decades after the end of the Cold War and the ensuing demise of communism in central and eastern Europe.
"The Soviets killed Polish elites in Katyn 70 years ago. Today, the Polish elite died there while getting ready to pay homage to the Poles killed there," former Polish president and Solidarity leader Lech Walesa told AFP.
"Jesus, Holy Mary, it's an inconceivable tragedy, an inconceivable disaster."
The European Union -- which counts Poland as its biggest erstwhile communist member state -- declared Monday a day of mourning, as world leaders took turns expressing shock and condolences.
"Today, there are heavy hearts across America," said US President Barack Obama, remembering "a distinguished statesman ... widely admired in the United States as a leader dedicated to advancing freedom and human dignity."
German Chancellor Angela Merkel was "deeply shocked", while French President Nicolas Sarkozy hailed Kaczynski as a man "driven by ardent patriotism, who dedicated his life to his country."
Putin told Russian television: "This is first and foremost Poland's tragedy and that of the Polish people -- but this is also our tragedy, and we mourn with you and grieve with you."
Reax: Shock and sorrow at Kaczynski death
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