The Ukrainian capital Kyiv has been subjected to an air attack by Russia, described by one official as "exceptional in density". At least three people were injured in the barrage, which used both drones and missiles, officials said. Video on social media showed air defense systems shooting down missiles over the city. Russia has stepped up its air campaign in recent weeks, ahead of an expected Ukrainian offensive in the south. The air raid alert sounded at around 02:30 local time (23:30 GMT Monday) and was lifted two hours later in the eighth attack to hit the capital this month. The head of Ukraine"s armed forces, Valerii Zaluzhny, said Russia attacked Kyiv from the north, south and east and that 18 air, sea and land-based missiles had been used. He added that all the missiles were shot down by Ukraine. Serhiy Popko, head of the Ukrainian capital"s military administration, described the barrage as being the "maximum number of attack missiles in the shortest period of time". "According to preliminary information, the vast majority of enemy targets in the airspace of Kyiv were detected and destroyed," he added. Kyiv residents were warned to keep away from windows as debris from intercepted missiles fell from the sky. Mayor Vitali Klitschko said rocket debris had fallen in central districts, including on the city"s zoo. The Solomyansky district, which includes the international airport, is reported to have been the hardest hit. Popko said that a fire that broke out in a non-residential in the district has since been put out. In the past few days, President Volodymyr Zelensky has been on a European tour, in which he has been promised several billion dollars worth of military equipment by Western allies, including UK Prime Minister Rishi Sunak and President Emmanuel Macron of France. Since Russia invaded Ukraine, thousands of civilians and combatants have been killed or injured, cities and towns have been destroyed in the fighting, and nearly 8.2 million Ukrainians have been registered as refugees in Europe, with 2.8 million of them in Russia. — BBC