WARSAW, Poland — Some 100,000 Poles filled Warsaw's Pilsudski Square Saturday for a memorial to the 96 people killed in a plane crash a week earlier, standing silent for two minutes before emergency sirens screamed and church bells pealed.

The crowd waved white-and-red Polish flags with black ribbons of mourning affixed to them. A massive white stage, a large cross in the center, was flanked by oversized photos of the dead, including President Lech Kaczynski.

The names of the dead were read aloud, starting with the president and his wife, Maria, while Marta, their only child, and Jaroslaw Kaczynski, the president's twin brother and former prime minister, looked on. Others at the service included former President Lech Walesa, Prime Minister Donald Tusk and acting president Bronislaw Komorowski.

"Our world went crashing down for the second time at the same place," Komorowski said of the crash near Russia's Katyn forest, site of a World War II massacre of Polish officers.

The ceremony is the first of two days of memorials and was to be followed by a funeral Mass for the first couple at Warsaw's St. John's Cathedral.

Among the mourners was Teresa Winkler, 76, who came to honor a president "who took care of the people forgotten by society," such as aging World War II soldiers and forgotten Solidarity activists. "He was a real patriot and a real Pole," Winkler said. "I am afraid it will be hard to find another president like Kaczynski."

Nearby was a group of Chechen refugees who said they were there to honor the first lady for her charity work and efforts to help them.

Members of Solidarity, the freedom movement that Kaczynski supported and that still exists as a labor union, waved their banners.

A state funeral for the president and his wife is set for Sunday but some world leaders canceled their plans to go, citing the volcanic ash cloud hanging over Europe, leaving numerous airports closed.