A Russian missile attack hit critical infrastructure in Kyiv on Saturday morning and explosions rang out in the Dniprovskiy district of the Ukrainian capital, a senior presidential official and other officials said.  Reuters journalists heard a series of explosions in Kyiv before an air raid siren sounded in Kyiv. Officials told residents to take shelter.  "Missile attack on critical infrastructure facilities. Details are being checked," said Kyrylo Tymoshenko, deputy head of the president's office.  Kyiv's military administration said an infrastructure facility had been hit, but did not say which.  "Explosions in Dniprovskiy district. All agencies heading to the site. Stay in your shelters!" Kyiv Mayor Vitali Klitschko wrote on Telegram.  He said the debris of a missile came down on a non-residential area in the Holosiivskiy district in the west of Kyiv.  Russia has been pounding Ukraine's vital energy infrastructure with missiles and drones since October, causing sweeping blackouts and disruptions to central heating and running water as winter bites.