SMOLENSK, Russia - An aging Russian airliner carrying Polish President Lech Kaczynski and members of his country's military, political and church elites crashed in thick fog Saturday as it took them to a ceremony marking the 70th anniversary of the slaughter of thousands of Polish military officers by Soviet secret police.

Poles wept before their televisions, lowered flags to half-staff and taped black ribbons in their windows after hearing that the upper echelons of the establishment lay dead in woods a short drive from the site of the Katyn forest massacre, one of Poland's greatest national traumas.

Russia's Emergency Ministry said there were 97 dead, 88 in the Polish state delegation. Poland's Foreign Ministry said there were 89 people on the passenger list but one had not shown up for the roughly 1 1/2-hour flight from Warsaw's main airport.

Poland called for two minutes of silence across the country today and declared a week of mourning. Medevedev declared Monday a day of mourning in Russia.

Thousands of people, many in tears, placed candles and flowers at the presidential palace in central Warsaw. Many called the crash Poland's worst disaster since World War II.

Twenty monks rang the Zygmunt bell at Krakow's Wawel Cathedral - the burial spot of Polish kings - a tolling reserved for times of profound importance or grief.

The crash also shocked Russia. Sensing the depth of the tragedy for Poland, Prime Minister Vladimir Putin personally took charge of the investigation and very quickly and publicly offered condolences, along with Russian President Dmitry Medvedev.

"On this difficult day the people of Russia stand with the Polish people," Medvedev said, according to the Kremlin press service.

Chunks of the plane were scattered widely amid leafless trees and small fires in woods shrouded with fog. A tail fin with the red and white national colors of Poland stuck up from the smoking debris. Early indications pointed to pilot error in heavy fog as a factor in the crash, officials said.

On board were the national bank president, deputy foreign minister, army chaplain, head of the National Security Office, deputy parliament speaker, Olympic Committee head, civil rights commissioner and at least two presidential aides and three lawmakers, the Polish foreign ministry said. Kaczynski's wife, Maria, also died.

"This is unbelievable - this tragic, cursed Katyn," Kaczynski's predecessor, Aleksander Kwasniewski, said on TVN24 television.

It is "a cursed place, horrible symbolism," he said. "It's hard to believe. You get chills down your spine."