MOSCOW, March 27 -- Russian President Vladimir Putin on Tuesday signed a decree declaring Wednesday a day of national mourning for the victims of a major fire in a mall in the Siberian city of Kemerovo, which killed at least 64 people.

The national flag will be flown at half-mast, while recreational radio and TV programs and other activities will be canceled.

The decree also ordered the government and local authorities to provide assistance to the families of the dead and injured.

The fire, one of the deadliest in Russia in recent years, broke out at the Winter Cherry shopping mall in downtown Kemerovo Sunday afternoon.

Putin laid flowers at an improvised memorial for the victims near the gutted mall and met officials, rescuers and local residents.

Local residents organized a rally in the central square, demanding punishment for those responsible for the tragedy.

Putin met their representatives and promised justice after the investigation is over.

Alexander Bastrykin, head of the investigating committee, said investigators are examining two possible reasons for the accident: a short circuit or, less likely, use of open fire.

Putin blamed "criminal negligence and mismanagement" for the tragedy.

On Monday, the Kemerovo region declared three days of mourning starting Tuesday. It was followed by several other regions and cities.