Children's drawings are placed at a police barrier in front of a collapsed supermarket (rear) in Riga November 23, 2013. The last part of the supermarket roof collapsed to the ground in the Latvian capital on Saturday but there were no further injuries in a disaster that has so far claimed 54 lives.  [Photo/Agencies]

RIGA - The death toll from the roof collapse at a supermarket in the Latvian capital Riga on Thursday has risen to 54, an official said on Saturday.

The chance of finding more survivors is zero, said State Secretary of the Ministry of the Interior Ilze Godmane at a press conference.

A collapse happened on Saturday in an area where rescue workers were not working. For safety reasons, the rescue work has been stopped and will resume on Sunday, Godmane said.

The supermarket, built in 2011, belongs to the Lithuanian-owned Maxima chain, the second largest retailer in the country.

The reason for the collapse is currently unknown, but reports have said a garden with trees and plants was being built on the store's sizeable roof, which might have violated construction regulations and triggered the collapse.

Latvia on Saturday began three days of mourning over the tragedy, which is the worst accident in the Baltic country in over 20 years.

Latvian President Andris Berzins told local media on Saturday that the accident should be viewed as a murder case and he called for investigation as fast as possible.