At least 20 people were killed and nearly 100 were injured when the snow-laden roof of an exposition hall collapsed near the southern Polish city of Katowice.
According to police, at least 80 people had already been hospitalised and another 100 were still believed to be trapped under the corrugated metal roof at 8pm Irish time.
Rescuers with sniffer dogs and lifting equipment were working to reach the survivors, with ambulances at the ready to rush the injured to hospital.
Earlier, firefighters said that as many as 500 people may have been inside the hall when the roof caved in during a carrier pigeon exposition in the Katowice suburb of Chorzow.
'The snow accumulated on the roof of the hall could have been the cause of the accident,' local fire brigade spokesperson Janusz Jonczyk told AFP.
Poland is experiencing its coldest winter in several decades. The death toll from a cold snap this winter stood at 199 on Saturday but was expected to top 200 over the weekend.
A cold snap has knocked temperatures to as low as -30C in parts of Europe.
The freeze has killed the poor and vulnerable across the region, disrupted transport, highlighted gas supply problems and frozen parts of the Black Sea.
Earlier this month, 15 people died at an ice skating rink in the town of Bad Reichenhall in southern Germany when a 34-year-old roof collapsed under the weight of fallen snow. All but three of the dead were children.
