Large sections of a supermarket roof collapsed on shoppers in Latvia's capital Riga on Thursday killing at least 45 and injuring dozens more, rescue officials said.
The incident happened at 6pm local time, when the Maxima store was busy with customers on their way home from work.
There are fears that more people may be buried in the rubble. Dozens of people waited near the wreckage for news of their relatives. The number of those trapped is so far unknown.
"I have a wife there. There is no information about her, whether she is dead or alive. Wherever I call, there is no information," Igor Umanov told Reuters Television.
After 15 hours of rescue work, he said he still believed his wife was alive.
A spokesman for the Maxima store said that five of its employees had been injured, two had been taken to hospital but three had not yet been found.
"Of course, psychologically it is very hard to work, taking into account that three firefighters have died," Latvian rescue services spokeswoman Inga Vetere told Latvian radio.
The reason for the collapse was still not known, but rescue and police officials said workers had been building a garden on the roof as part of the supermarket's original design.
Rescue workers were called to the store, situated among gray, Soviet-era housing in a suburb, after an initial partial roof collapse. Then a second section gave way.
"It is clear that there has been a problem with fulfillment of construction requirements," Rihards Kozlovskis, the interior minister, told Latvian TV by telephone.
Valdis Dombrovskis, the Baltic nation's prime minister, told Latvian TV that the rescue work would probably go on for many hours.
The RIA Novosti news agency quoted Nils Usakovs, Riga's mayor, as saying 70 people were still in the building.
Rescue services said 40 injured people had been rescued and police sniffer dogs were searching for people still trapped.
"As we are still working inside, the situation may change," Normunds Plegermanis, deputy head of rescue and emergency service, said.
"Falls are happening from time to time. Therefore it is very dangerous to work inside," he said.
TV pictures showed the Maxima store surrounded by fire-fighting vehicles and ambulances with rescue workers using mechanical cutters to clear debris from the single-story concrete and glass building.
Latvian TV said three cranes were working to remove concrete blocks from the roof so that rescuers could get to those inside, but firefighters feared another collapse.
The police will launch an investigation into the disaster.
Local media reported that the Maxima supermarket, had been awarded an architecture prize when it was completed in 2011.
Latvia, which joins the Eurozone next year, has been recording strong economic growth after a deep recession in the years following the global credit crisis.
It is still one of the poorest countries in Europe, the legacy of nearly 50 years of Soviet rule that came to an end in 1991.