Riga, Nov 22 (IANS): At least 32 people, including three firefighters died and 34 others were injured after the roof of a supermarket collapsed in Latvia's capital Riga, officials said Friday.

Andris Ameriks, deputy mayor of Riga said that some 50 people were still trapped following the accident, which occurred in a densely populated neighbourhood in Riga Thursday, according to Xinhua.

Ilze Buksa, a spokeswoman for Latvia's emergency medical service, said some of the injured had been hospitalised, while others received treatment on the site and went home.

The 500-sq.m supermarket, built in 2011, belongs to the Lithuanian-owned Maxima chain, the second largest retailer in the country.

The reason for the collapse is still 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.

Rescue work is proceeding slowly as both the rubble and remaining sections of roof are at risk of further collapse.

Rescue officials are unsure about the number of survivors under the rubble but fear that the death toll will rise.