Poland grieves as death toll from collapsed roof hits 66

Poland declared an official period of mourning after the steel roof of a packed exhibition centre collapsed in sub-zero temperatures, killing at least 66 people.

The accident in Katowice, southern Poland, was the country's worst in two decades, and was blamed by some on the extreme weather conditions that have swept through eastern and central Europe.

The fire brigade said the roof collapsed on Saturday evening under the sheer weight of snow. The building's owners have denied that claim and insisted that the snow was regularly cleared from the roof. The government has ordered the roofs of all public buildings to be swept clean of snow.

Another theory is that the extreme cold - temperatures have dropped as low as minus 30C in Poland this month - had weakened the roof's steel rafters, which became brittle and simply snapped.

The exhibition centre was packed at the time of the collapse, with 700 enthusiasts attending an annual event devoted to the sport of pigeon racing.

A police investigation into precisely what went wrong in Katowice is under way. It will examine how a building constructed as recently as the 1990s using supposedly state-of-the art technology could collapse like a house of cards.

Several of the building's emergency exits were reportedly locked and people weresaid to have struggled to smash toughened glass with chairs to get to safety.

Emergency services were last night preparing to tear down what was left of the exhibition centre, having given up hope of finding more survivors. Nobody has been pulled out of the debris alive since Saturday night, despite emergency services pumping warm air into the wreckage in order to increase people's chances of survival. Rescue efforts have been conducted in temperatures of minus 15C and in poor light using sniffer dogs.

About 150 people were injured, many of whom are still in hospital.

Relatives of the victims gathered at the accident site last night in an attempt to find out more. One survivor, Tadeusz Dlugosz, related how he had climbed out of the wreckage only to learn that his 26-year-old son, who had been visiting another exhibit when the roof collapsed, had died. "It was his idea to come to the fair ... and he found his grave there," Mr Dlugosz said.

Piles of rubble lay alongside sections of the corrugated steel roof, while pigeons perched on icy rafters surveying the wreckage yesterday.

"It took just a few seconds for this roof to collapse and it looked like a plane crashed on top,'' said Jerzy Kozrych, a survivor. "There were hundreds of people trying to crawl out, a total mess, like Judgement Day."

Witnesses reported hearing "something snap like a match" before the roof caved in and described how they had had to climb over one another. A second section of the roof collapsed while rescue efforts were under way.

President Lech Kaczynski declared a national state of mourning until Wednesday. "This was the greatest tragedy of the third Polish Republic," he said. It was Poland's worst disaster since 1987, when a passenger airliner crashed just outside Warsaw, killing 183.