Investigators blame snow buildup, design flaws or poor maintenance.
MOSCOW -- Rescuers paused repeatedly in hopes of hearing survivors trapped under concrete and metal beams Thursday after a snow-laden roof collapsed on one of Moscow's biggest markets, killing at least 56 people.
Investigators blamed the disaster on a buildup of snow after a harsh winter, design flaws or poor maintenance.
Workers used metal cutters, hydraulic lifters and pick axes to clear the rubble from the Basmanny market and knelt down to shout into the wreckage in search of survivors. Dogs helped with the search and bright searchlights illuminated the area after dark.
One man, a 52-year-old herb seller from Azerbaijan, said he left the market just before the concave roof gave way around 5 a.m.
"I heard a loud noise and I fell to the ground and lost consciousness. When I came to, I was lying by the entrance," Ukhtai Salmanov said, his clothes covered in dust. "There was smoke and people were screaming."
Fighting back tears, he said he was unable to save his three sisters, who also worked in the huge circular building.
At least 56 people were killed and 32 injured, Emergency Situations Ministry spokeswoman Natalya Lukash said.
Emergency officials said it was impossible to say how many people had been in the market at the time of the collapse, but survivors and witnesses said there could have been more than 100.
The market, where produce, meat and dairy products are sold along with household goods, was closed for retail sales, but wholesalers were getting an early start. Some market workers also were reportedly sleeping in the building.
Officials expressed relief the roof hadn't collapsed later Thursday when the building would have been filled with shoppers taking advantage of the first day of a three-day holiday marking Defenders of the Fatherland Day, which honors Russia's armed forces.
Virtually all the victims were believed to be workers from Azerbaijan and other former Soviet republics, among the thousands who have poured into the Russian capital to fill low-paying jobs.
Cries and shouts rang out from the crowd of relatives gathered near the site as emergency workers read the names of the hospitalized. One woman was pulled away, wailing, after hearing her brother was killed.
"I have a cousin there. I've been calling him since morning but at first there was no answer, and now the phone does not ring," said Eshkin Mekhvaliyev, a young Azerbaijani man.
Medical workers tried to help a man trapped under a slab of concrete that left only his hand visible, giving him painkillers through an intravenous drip.
Machines were brought in to blow warm air into the rubble to try to keep victims alive in the near freezing temperatures.
Trapped survivors called relatives using cell phones, helping rescuers find them, said Yuri Akimov, deputy head of the Moscow department of the Emergency Situations Ministry. But hours passed with no rescues.
The Basmanny market, also known as Bauman after the technical institute in the neighborhood, is in an east-central area of the Russian capital and is not among those most popular with foreign tourists.
Grief occasionally spilled over into anger and accusations, fiercely rejected by officials, of a slow response to the disaster.
"They knew we were from the Caucasus," Aktai Soldan said bitterly. "If there had been Russians in the rubble, they would have done more to help."
Emergency workers had to shift their efforts in the afternoon to fighting a fire started by a spark from an electric saw on the edge of the building, sending acrid smoke billowing into the air. But Emergency Situations Ministry spokesman Viktor Beltsov said it posed no threat to anyone in the wreckage.
The probable cause of the collapse was either the buildup of snow, design flaws or maintenance errors, Moscow Prosecutor Anatoly Zuyev said. Prosecutors have opened a criminal investigation on charges of negligence leading to deaths, the RIA-Novosti news agency reported.
Two to three inches of wet snow fell overnight in Moscow, on top of nearly 19 inches earlier, according to the Russian Weather Service.
The tragedy came after snow-covered roofs collapsed in Poland and Germany this year, killing some 80 people and raising troubling questions about safety standards.
Moscow Mayor Yuri Luzhkov said the market was built in 1974 and its roof was designed to handle snow.
The market was designed by Nodar Kancheli, the architect behind Moscow's Transvaal water park, where the roof collapsed in 2004, killing 28 people. Prosecutors have blamed that collapse on design flaws.
Kancheli went to the market after the collapse and was questioned by investigators, Russian news agencies reported.
"I think one possibility is a big buildup of snow," Kancheli told Ekho Moskvy radio. "And they set up kiosks on the mezzanine, which was not originally planned."