TV pictures before dawn showed the wreckage of the Maxima store, in a suburb of grey, Soviet-era housing, surrounded by fire trucks and ambulances after the roof collapsed on Thursday when the store was full of shoppers on their way home from work.

The store, estimated at around 500 square meters (5,380 square feet) in size, was bathed in spotlights as diggers and rescue workers cleared away the wreckage.

"Twenty-one dead found, searching continues," the State Fire and Rescue Service said in a tweet.

Earlier, ambulance service spokeswoman Ilze Buksa said that 28 people had been injured and taken to hospital.

It was not clear what caused the collapse, but Interior Minister Rihards Kozlovskis said: "It is clear that there has been a problem with fulfilment of construction requirements."

Around 25 people waited near the wreckage for news of their relatives. The number of those trapped was 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 said. After 15 hours of rescue works, he said he believed his wife was alive.

Prime Minister Valdis Dombrovskis said that rescue work may take a long time.

Rescue workers were called to the store, which according to local media had been awarded an architecture prize when it was completed in 2011, late on Thursday. Several were injured by a second collapse because of the building's weakened structure.

Rescue workers were stopping work periodically to listen for survivors and for the sounds of mobile phones in the wreckage, a report said.

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 said.

Early on Friday, cranes were working to lift and take off concrete blocks which are hampering rescue efforts, state fire and rescue service chief Oskars Abolins said.

"As we have to search all the rubble and the whole construction, rescue work might continue for another day," he said.

Local media said workers had been building a roof garden on the store.

Former Soviet Latvia, which joins the euro zone next year, has been recording strong economic growth after a deep recession in the years following the global credit crisis, but it is still one of the poorest countries in Europe.


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