Russia launched a fresh wave of attacks on the Ukrainian capital of Kyiv early Tuesday, sparking fires in parts of the city, officials said. Tymur Tkachenko, head of the capital's military administration, said two storage areas were hit and set on fire in the Holosiivskyi district just outside the city centre. Mayor Vitali Klitschko said drone debris had hit the ground in an open area in an eastern suburb and cars had been set ablaze. Reuters witnesses reported several explosions in the city. Six people were injured elsewhere in a town outside Kharkiv, its regional governor Oleh Syniehubov said. The attacks came just hours after Russian president Vladimir Putin vowed emphatic retaliation to Kyiv's recent long-range attacks on refineries, tankers and terminals that have caused widespread fuel shortages. "Wherever they attempt to strike Russian territory, we will respond in kind, but our strikes will be several times more powerful," Putin told a meeting with pro-Kremlin activists.