Polish President Lech Kaczynski and scores of others are believed to have been killed in a plane crash in Russia.
Officials in the Smolensk region said no-one had survived after the plane apparently hit trees as it came in for landing in thick fog.
Several other government figures, including the army chief of staff, were also thought to have been on board.
They were in Russia to mark the 70th anniversary of the Katyn massacre, when the Soviets killed thousands of Poles.
The BBC's Adam Easton in Warsaw says the crash is a catastrophe for the Polish people.
He says Prime Minister Donald Tusk was reportedly in tears when he was told.
Plane 'hit trees'
The Russian emergencies ministry told Itar-Tass news agency the plane crashed at 1056 Moscow time (0656 GMT).
Ministry spokeswoman Irina Andrianova said it had been flying from Moscow to Smolensk, but had no details on the identities of those killed.
Smolensk regional governor Sergei Antufiev told Russian TV that no-one had survived.
"As it was preparing for landing, the Polish president's aircraft did not make it to the landing strip," he said.
"According to preliminary reports, it got caught up in the tops of trees, fell to the ground and broke up into pieces. There are no survivors in that crash.
"We are clarifying how many people there were in the [Polish] delegation. According to preliminary reports, 85 members of the delegation and the crew."
Russian investigators said there were a total of 132 people on the plane.
The president was flying in a Tupolev 154, a plane that was designed in the 1960s and capable of carrying more than 100 passengers.
Our correspondent says there had been calls for Polish leaders to upgrade their planes.
As well as the president and his wife, Maria, a number of senior officials were also said to be on the passenger list.
They included the army chief of staff Gen Franciszek Gagor, central bank governor Slawomir Skrzypek and deputy Foreign Minister Andrzej Kremer.
Mr Kaczynski has been a controversial figure in Polish politics, advocating a right-wing Catholic agenda.
He has opposed rapid free-market reforms and favoured retaining social welfare programmes.
“Soft despotism is a term coined by Alexis de Tocqueville describing the state into which a country overrun by "a network of small complicated rules" might degrade. Soft despotism is different from despotism (also called 'hard despotism') in the sense that it is not obvious to the people."