RIGA, Latvia -- Rescuers searched Saturday for 10 missing people who may have been killed in the collapse of a supermarket roof, a disaster which the nation's president described as "murder."

Fifty-two deaths have been confirmed from the structural failure on Thursday. Police spokesman Dairis Anucins said there were 10 reports of missing persons who could have been at the supermarket.

President Andris Berzins called it a case of murder.

"This is a case where we need to say clearly that an enormous number of defenceless people were killed, and that's how we should proceed," Berzins said.

Some 40 people were wounded, including 13 firefighters, and 23 people remained hospitalized as of Saturday afternoon, police said.

It was the worst accident in the Baltic country since it regained independence in 1991. The government has declared three days of mourning.

Laila Rieksta-Riekstina, head of the state's child welfare department, told Latvia Radio that 16 children lost parents in the accident. Three of them lost both parents.

Rescue service spokeswoman Viktorija Sembele said some 3,200 square feet of ruins -- approximately one-sixth of the total damaged area -- remained to be searched as of Saturday morning.

Sembele said there was a chance more victims could be found in that area, which is particularly dangerous due to the risk of further collapse. Firefighters are working in decreased numbers in that area to minimize the chance of injury.

Rescue workers decided to stop the operation early Saturday and consult with engineers before continuing, she said.

Preliminary reports indicate the roof caved in due to either faulty construction or building activities on the roof, where workers were creating a garden area and children's playground for a new high-rise residential building adjacent to the supermarket.

Pictures show that a large amount of building materials, including bags of soil for the garden, were left in areas of the roof that, according to Riga city officials, could have been vulnerable to heavy loads.

Police have launched an investigation, which could take several weeks to complete.

Riga Mayor Nils Usakovs wrote in this Twitter account Saturday that once the investigation is over the supermarket ruins would be razed. He also suggested that the incomplete residential building might be torn down.