Throughout the staunchly Roman Catholic country, millions flocked to churches to pay their respects to the victims. The scenes echoed those after the death of Polish-born Pope John Paul II nearly five years ago.
Kaczynski's body was flown into Warsaw's military airport after a farewell ceremony attended by Russian dignitaries including Russian Prime Minister Vladimir Putin.
In Warsaw, the president's twin brother Jaroslaw, a former prime minister, knelt on the tarmac and pressed his head against the flag-draped coffin. A solemn tribute was also paid by his devastated only child - daughter Marta.
Acting President Bronislaw Komorowski, Prime Minister Donald Tusk and other senior Polish officials were also there to pay their respects during a short religious ceremony.
In a moving mark of respect, church bells pealed at noon and emergency sirens shrieked for nearly a minute before fading into silence. Hundreds bowed their heads, eyes closed, in front of the presidential palace. Buses and trams halted in the streets.
No date for a funeral has been set.
The presidential jet, carrying many of Poland's political and military leaders, crashed in western Russia as it was trying to land at a military airbase in thick fog.
Also among the dead were Poland's army chief of staff, the navy chief commander, and heads of the air and land forces.
The jet's passengers had been bound for a 70th anniversary memorial service for the 22,000 leading Poles massacred by Stalin's secret police in the Katyn forest during the Second World War, a historic wound which has still not healed.
As intensive investigations went on, questions were being asked about why the jet's two experienced air force pilots ignored repeated advice from Russian ground control to take the Tupolev 154 to another airport. At least one other plane had already been diverted.
Russian officials say pilots ignored warnings that they were flying too low.
Experts say the crew may have been ordered to press on with the landing by the president or a senior military commander on board.
A government source admitted that Kaczynski would have suffered political embarrassment if he had missed the Katyn ceremony. He was said to have seen the trip as the unofficial start of his campaign for a presidential election.
Polish aviation sources said Kaczynski had a record of being 'demanding' with his plane's pilots.
Despite bad weather being blamed for the crash, analysts said there would inevitably be speculation in Poland that the Russians were somehow involved.
It was not the first time the presidential plane - a 26-year-old Russian-made Tupolev-154 - had encountered difficulties.
It had been grounded during a state visit to Mongolia 16 months ago owing to technical problems, leaving the Polish leader to charter a private jet for the next stage of his tour to Japan.
There have been 16 crashes involving Tupolev-154s since 1994, killing 1,727 people, and Poles have been asking why their president was using an aircraft with such a poor safety record rather than fly with the Polish state airline LOT whose entire fleet is Western-made.
The Tupolev clipped the tops of trees as it tried to land at Smolensk, lurching sideways and breaking into pieces. Wreckage including engines and a large part of the red and white tail were strewn over a forest less than a mile from the runway.
Radio communication with the plane had been lost just before 8am yesterday.
Mr Putin said he would personally lead a commission of inquiry into the accident, while the Polish authorities announced that they would hold their own investigation into what commentators described as one of the worst tragedies to befall the country since the Second World War.
Edward Lucas, a leading expert on East European affairs, said: 'Although there is no evidence that the crash was caused by sabotage, many Poles will think foul play was involved because of the historical parallels with Katyn.
Polish Prime Minister Donald Tusk was reported to have wept when told of the disaster.
The Queen expressed her 'deepest sympathy' to the Polish government and people while Gordon Brown said the whole world would be 'saddened'.
Clarence House said the Prince of Wales and the Duchess of Cornwall, who visited Poland last month, were 'deeply upset'.
As president, Mr Kaczynski wielded considerable political power and was accused by critics of interfering in policy decisions.
Together with Jaroslaw he founded the Law and Justice party in 2001, which stresses the traditional values of Roman Catholicism.
Jaroslaw now leads the Conservative opposition. At the age of 12, the pair shot to fame as stars of the 1962 Polish children's film Two Who Stole the Moon.
In the Seventies, Lech followed his brother into the anti-Communist Solidarity movement led by Walesa.
In the wake of the 2005 election, Poland had both Kaczynskis holding the reins of power - Lech as President and, from July 2006 to November 2007, Jaroslaw as Prime Minister.
World leaders pay tribute
German Chancellor Angela Merkel: 'The only thing I can say now is that I'm in deep shock about the plane crash and the death of the Polish president.'
U.S. President Barack Obama: 'Devastating to Poland, to the United States, and to the world. President Lech Kaczynski was a distinguished statesman who played a key role in the Solidarity movement, and he was widely admired in the United States as a leader dedicated to advancing freedom and human dignity.'
Italian Prime Minister Silvio Berlusconi: 'I was a personal friend of President Lech Kaczynski. This a grave moment of mourning for a friendly country and Italy joins in the mourning with all its heart.'
Prime Minister Gordon Brown: 'President Kaczynski was one of the defining actors in Poland's modern political history. From his role in the Solidarity movement to his long and distinguished career in public service.He will mourned across the world and remembered as a passionate patriot and democrat.'
Dutch Prime Minister Jan Peter Balkenende: 'This is a disaster of unprecedented magnitude. For the families, for all the Polish people. That this happens on such a scale is beyond comprehension.'
French President Nicolas Sarkozy: 'France loses a friend who was profoundly attached to developing relations between our two countries. Driven by an ardent sense of patriotism, Lech Kaczynski dedicated his life to his country. A tireless defender of the ideas in which he believed, he always fought with conviction for the values that underpinned his entry into politics.'
Israeli President Shimon Peres: 'The tragedy is a terrible blow to the Polish people and the entire world. President Kaczynski and his wife did much work to bring reconciliation between the Israeli and Polish peoples, and made a significant contribution to help heal the wounds of the past and build a better common future.
U.N. Secretary-General Ban Ki-moon: 'President Kaczynski served his country and people with distinction and conviction.'
Hungarian President Laszlo Solyom: 'Friendship with Hungary, which we celebrated every year together, had a special place in his heart.'
Jerzy Buzek, president of the European Parliament: 'It's with great sadness that I learnt about the shocking news of the crash -- on board was my friend and a great Polish politician, Lech Kaczynski. It is with a heavy heart that I think of all those with him on board of the plane.'
Lithuanian President Dalia Grybauskaite: 'I am personally shocked because I spoke with him just a day before yesterday. We have lost a good friend.'
Lithuania Prime Minister Andrius Kubilius: 'Poland President's death is a huge tragedy. Lithuania has lost a true friend.'
Source : dailymail