At least six people have been killed and dozens more are feared trapped after the roof of a supermarket collapsed in the Latvian capital, Riga.
Two of those killed were emergency workers, officials said. At least 35 people have been injured.
It is not yet clear what caused the collapse. A BBC correspondent says a garden was being constructed on the roof of the supermarket at the time.
The 500 sq m (5,000 sq ft) store, run by the Maxima chain, opened in 2011.
The collapse happened just before 18:00 local time (16:00 GMT), when the store was busy with people shopping on their way home from work.
It brought down the supermarket’s high walls and windows in a ripple effect that filled the shell of the building with rubble and left shattered glass on the street, witnesses said.
About 20 minutes later another part of the roof caved in, trapping rescue workers who were trying to reach survivors.
Witness Anita Daukste said: “It was crashing, most people started crying and screaming. It was certain that those left inside after the first collapse would not be alive after the second fall.”
Dozens of emergency teams are at the scene and as many as 50 people are feared trapped in the rubble.
TV pictures showed rescue workers using their hands and crowbars to pull away rubble.
Latvian media later said three cranes had been brought in to remove concrete.
“There are six people dead, four of them are shop clients and two are firefighters,” Latvian rescue service spokeswoman Viktorija Sembele told Reuters.
She said 35 people had been injured so far and rescue efforts would continue through the night.
Witnesses said customers tried to run out after the first part of the roof collapsed but the supermarket’s electronic doors closed, trapping them inside.
Normunds Plegermanis, deputy head of rescue services, said emergency teams faced difficult conditions.
Falls are happening from time to time… it is very dangerous to work inside,” he said.
Rumours of an explosion have been denied by reporters on the scene, says the BBC’s Caucasus correspondent Damien McGuinness.
He says the most likely explanation being considered is the weight of soil which was being used to plant a winter garden on the roof.
As the rescue operation continued, Prime Minister Valdis Dombrovskis confirmed that police had launched a criminal investigation.
Riga Mayor Nils Usakovs announced he was cancelling his leave and calling an emergency meeting of municipal and rescue services for Friday, AFP reported.
“As soon as rescue work has finished, construction experts will investigate the causes,” said a news release from his office.