According to a Russian TASS source, more than 3,000 shoppers have been evacuated from the building.
The gunman was armed with a shotgun, Swedish media has reported
One person has reportedly been injured
A second video on her Twitter feed shows tear gas canisters dropping from the sky and landing within yards of television crews.
Police treating incident as terrorist attack
Two people apprehended
Man exchanged shots with police
Shooter possibly still active
Police shot at car driver