Citizens of Tyumen in Russia's Siberia began three days of mourning on Wednesday for victims of a plane crash that killed 31 people and injured 12 others.

Tyumen Governor Vladimir Yakushev, in an official mourning message, expressed "sincere condolences to the families of all those who died in the terrible catastrophe."

During the mourning period, flags will be flown at half mast and all entertainment TV and radio broadcasts will be canceled.

A cross has been set up at the site of the crash, where flowers were placed and candles were lit.

Yakushev also agreed to install a temporary monument in central Tyumen for local residents to bring flowers and candles there and express their grief.

A French-Italian-made passenger plane, carrying 39 passengers and four crew members, went down early Monday shortly after take-off from Tyumen in western Siberia. According to the list of the dead and injured in the air crash, 36 people are Tyumen residents.

According to the state Investigative Committee's announcement, failure to de-ice the aircraft before take-off was the most likely cause of the disaster.