JIM LEHRER: Now: Poland's great national tragedy.
Ray Suarez has that story.
RAY SUAREZ: Signs of mourning were everywhere today in Warsaw, two days after president Lech Kaczynski was killed in a plane crash, along with dozens of other high-ranking Polish officials.
TOMEK SWENTOISKIE, Poland: The people are sad. Nobody is -- is happy. We just walk to our jobs, do what we have to do. And we will see what will happen. But it's -- it's really a big tragedy for us.
RAY SUAREZ: President Kaczynski's body was returned Sunday, greeted by his daughter and his twin brother. Thousands lined the route from the airport to the presidential palace, where the body will lie in state for a week.
In all, 96 people died in Saturday's crash, when Kaczynski's Soviet-made plane went down near Smolensk, Russia, 275 miles west of Moscow. The victims included the president's wife, the Polish army and navy chiefs, the head of the national security office, and the president of the state bank.
They were heading to a memorial in the Katyn Forest, where Soviet secret police executed thousands of Polish military officers 70 years ago, during World War II.
Former Polish president Lech Walesa:
LECH WALESA, former Polish president (through translator): We lost the elite of this country, a part of them. It's very similar to the Katyn massacre. At that time, our head was taken away and cut off. Now, unexpectedly, we also lost great people from various political areas, and it will be very hard to replace them.
RAY SUAREZ: The Polish prime minister convened an emergency meeting this week to try to fill the gaps. The parliamentary speaker was named acting president. The investigation also proceeded amid questions about why the pilot rejected warnings from the control tower and repeatedly tried to land in dense fog. He crashed on the fifth attempt.
A reconstruction by the Russian air force showed the plane was too low and, at an angle, smashing into woods near the runway. In the meantime, condolences poured in from around the world. Polish immigrants across the U.S. attended memorial masses from New York to Arizona.
In Washington, the Polish Embassy lowered its flag to half-staff, and the U.S. State Department voiced hope for the future.
P.J. CROWLEY, U.S. assistant secretary of state for public affairs: This tragedy, you know, cut short these lives that will be felt deeply across the world, but their legacy will live on in a free and flourishing Poland.
RAY SUAREZ: A presidential election had been scheduled for October, but it's expected new elections will now be called within the next two months.