Tatarsky, a vocal supporter of Russia's war in Ukraine, died in an explosion at a St Petersburg cafe on Sunday evening. Twenty-four others were taken to hospital and six were in critical condition, the health ministry said. Videos posted on social media showed a blast and injured people on the street. It was not immediately clear who was responsible for the attack. But Ukrainian presidential adviser Mykhailo Podolyak blamed the blast on a Russian "internal political fight", tweeting: "Spiders are eating each other in a jar."