At least twelve people have died, dozens are wounded and many more are feared trapped after a supermarket roof suddenly collapsed in the Latvian capital Riga on Thursday evening. It happened while many people were shopping on their way home from work.

One eyewitness, Nadezhda, described the chaos: “Some tube exploded because there were construction works taking place on the roof of the supermarket. They were building a playground for children. Obviously they did something wrong and the roof did not hold this,” she said.

Three of the dead are understood to be firefighters who were killed when another part of roof fell as they searched for survivors.

Latvian Prime Minister Valdis Dombrovskis visited the scene.

“Police have started the investigation already. The criminal process has started about violating construction norms,” he said.

The supermarket, part of the Maxima retail chain, was built in 2011. It was even nominated for an architectural award.

On Friday morning police dogs joined the search for people trapped under the rubble.