Katowice, Poland ? Rescuers abandoned hope Sunday of finding survivors beneath the wreckage of an exhibition hall that collapsed, killing 66 people, and authorities were bringing in heavy equipment to demolish what little remained of the building.

The structure collapsed Saturday afternoon with an estimated 500 people inside, attending a pigeon racing exhibition. The last person rescued alive from the building was pulled out less than five hours later.

Rescue crews nonetheless worked through the night, using hand tools to carve through the sheet metal and snarled poles of the collapsed building so as not to risk harming any possible survivors as temperatures dropped to 1 degree. On Sunday, a day after the collapse, they stopped.

“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, he said.

A total of 66 people were killed and 160 injured, authorities said.