**Russian President Dmitry Medvedev has declared a national day of mourning on 7 December after a fire at a nightclub killed at least 109 people.**He said the fire was a criminal act and those responsible must be punished.
Officials say that fireworks inside the club caused the blaze and that most victims died from smoke inhalation.
More than 140 people were reported injured at the Lame Horse club in Perm, some 1,400km (870 miles) east of the capital Moscow.
Speaking on Saturday, Mr Medvedev said those responsible “have neither brains, nor conscience”, calling for the toughest possible punishment.
Russian officials said earlier they had arrested the owner of the nightclub and other suspects, following the accident on Friday night.
The Lame Horse nightclub had been celebrating its eighth anniversary, emergency services said.