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.
Officials said they were investigating three possible causes for the collapse: a buildup of wet snow that fell overnight, improper maintenance of the Basmanny market, which was built in 1974, and design flaws.
At least 32 other people were injured when the roof fell, Emergency Situations Ministry spokeswoman Natalya Lukash said.
Witnesses said there could have been more than 100 people inside when the roof fell between 5 and 6 a.m.
Moscow Mayor Yuri Luzhkov said the market was built in 1974 and its roof was designed to handle snow.
"There was a special gutter pipe that was always left open so the melted snow could run down, so there was no special need to have the roof cleared of snow," the mayor said.
Two to three inches of wet snow had fallen overnight in Moscow, on top of nearly 19 inches earlier, the Russian Weather Service said.
The market was designed by Nodar Kancheli, the architect behind Moscow's Transvaal water park. That building's snow-laden roof collapsed in 2004, killing 28 people, and prosecutors have blamed design flaws. The Basmanny market was among a number of buildings that were inspected after the water park accident.
Kancheli, who specializes in creating large interior spaces without supporting pillars, went to the market 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."
Prosecutors have opened a criminal investigation on charges of negligence leading to deaths, the RIA-Novosti news agency reported.
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 reportedly were sleeping in the building.
Officials expressed relief the roof hadn't collapsed later Thursday, when shoppers would have filled it for the first day of a holiday honoring Russia's armed forces.
Most of the victims were believed to be from Azerbaijan and other former Soviet republics.
Information from the New York Times and Washington Post was used in this report.
ROOF COLLAPSES IN EUROPE
Feb. 23: The snow-covered roof of a Moscow market, shown at right, collapses, killing at least 56 people.
Jan. 28: The roof over an exhibition hall in Katowice, Poland, falls, killing 65 people.
Jan. 2: The roof collapses over a skating rink in the German town of Bad Reichenhall, killing 15, most children.
Dec. 4, 2005: The roof over a swimming pool in Russian town of Chusavoi collapses, killing 14 people.
Feb. 14, 2004: The roof of a Moscow water park collapses, killing 28 people.