State media has reported that several people are injured – including both civilians and police.
The man is believed to have opened fire in a residential block towards the south of the city.
Kazan is the capital of the Tatarsta autonomous region in the south of the country.
The shooter is believed to have been a 34-year-old local armed with a rifle.
At least three people – a civilian, a special officer and a local policeman – are believed to have been gunned down.
More to follow…