At least 48 people died when a roof at a supermarket in the Latvian capital, Riga, collapsed on shoppers.
At least 36 others were injured, with most of them hospitalized.
Firefighters suffered casualties -- including three dead -- when a second part of the roof fell on them minutes after they arrived to aid those injured.
A survivor described the scene as the collapse took place on November 22: "It was crashing, most people started crying and screaming as it was sure that those who were left inside, after the first collapse, would not be alive after the second fall."
The accident occurred during the evening shopping rush-hour at the Maxima supermarket in the Riga suburbs.
It is unclear how many people might still be trapped under the rubble, but officials estimated dozens are still unaccounted for.
Rescue teams -- including three cranes -- are continuing a search for survivors among the ruins of the collapsed store. Sniffer dogs were also being used.
Workers had been building a winter garden on the roof, but the reason for the collapse is still unknown.
Police officials said the collapse is possibly related to flaws in the design of the building or poor construction work on the building, which was built in 2011.
Prime Minister Valdis Dombrovskis said a criminal investigation had begun.
"We are going to take more severe control measures on construction sites of this kind, especially on sites that are currently under construction or the construction is planned to start soon," Dombrovskis said.
Officials were calling on Riga residents to donate blood to help those injured. They also asked family members of the missing to call their mobile phones so that police could pinpoint where people might be trapped in the debris.
Based on reporting by AP and AFP