"The rescue operation is over," said Krzysztof Mejer, a spokesman for the government of the Silesia region. Thirteen rescue dogs from Poland and the neighboring Czech Republic indicated that there were no more bodies in the debris.
"We can confirm 66 people were killed and we don't expect anyone else to be found under the wreckage," he said.
The roof collapsed on Saturday afternoon, when an estimated 500 people were in the hall.
Working in bitterly cold temperatures, rescue crews had used hand tools to carve through the sheet metal and snarled poles of the collapsed building so as not to risk harming any potential survivors. Fire Chief Kazimierz Krzowski said that large machinery was now being called in to tear down the rest of the building.
"The parts of the structure that are not lying on the ground are a threat," he said.
One survivor, Tadeusz Dlugosz, climbed his way out of the twisted wreckage, only to find out his 26-year-old son, who had been visiting another exhibit when the hall roof collapsed, had been killed.
He was still at the site on Sunday morning, trying to find out where his son's body had been taken.
"It was his idea to come to the fair and he found his grave there," Dlugosz said. "I don't know which morgue he's in. I would like to see him and take him as quickly as possible."
At least 66 people were killed, said Janusz Skulich, head of the Silesia region fire brigade. Among the dead was a police officer who was providing security for the exhibition, said police spokesman Janusz Jonczyk, adding that there were at least 160 people injured.
Jonczyk said 51 of the victims had been identified by Sunday afternoon, including seven foreigners. Another police spokesman, Arkadiusz Szweda, said they included two Slovaks, two Czechs and one victim each from the Netherlands, Belgium and Germany.
People who escaped said two emergency exits were open, but other exits were locked, leaving others trapped.
Witness Franciszek Kowal, who got out onto a terrace and jumped about 13 feet to safety, saw people struggling to break windows to escape.
"Luckily nothing happened to me, but I saw a macabre scene, as people tried to break windows in order to get out," Kowal told The Associated Press. "People were hitting the panes with chairs, but the windows were unbreakable. One of the panes finally broke, and they started to get out by the window."
Attorney Grzegorz Slyszyk, who represents the company that owns the building, said he had no information on the reports, but that if exits were locked, the reason would be investigated.
Prime Minister Kazimierz Marcinkiewicz joined several thousand others packing Katowice's Cathedral of Christ the King on Sunday for a Mass led by Archbishop Damian Zimon for the victims.
President Lech Kaczynski declared a national state of mourning to last through Wednesday.
"This was the greatest tragedy of the third Polish Republic," Kaczynski said.
After the roof collapsed, people trapped in the wreckage used cell phones to call relatives or emergency services and tell them where they were.
Crumpled bird cages were scattered inside the building near the entrance, and dozens of white and brown pigeons perched on the twisted rafters.
Police said snow made the roof collapse, but Slyszyk, the attorney for building management, disputed that. He said snow had been removed regularly and that it was too early to speculate on a cause.
Some 1,300 firefighters, police officers and mine rescue workers from around the region were brought in to help.
The exhibition at the 110,000-square-foot hall in the Bytkow district of the city opened Friday.
The "Pigeon 2006" fair had more than 120 exhibitors, including groups from Belgium, the Netherlands, Germany, Ukraine and Poland, according to the fair's Web site. The gathering was devoted to pigeon racing, a sport in which homing pigeons are released and race home using their sharp sense of direction.