AFP reporters saw large columns of black smoke spreading over the capital's southern skyline in dramatic scenes, while flames could be seen burning on part of an oil complex in the southern Kapotnya district.A strong, unpleasant smell hung in the air, as the fire burned at the refinery through the morning.The strikes came as Russian President Vladimir Putin hosted Southeast Asian leaders at a summit in the central city of Kazan, about 700 kilometres (435 miles) east of the capital.Ukrainian President Volodymyr Zelensky praised the strikes in a post on social media, calling them a "fully justified response" to Russian attacks on Ukraine.The attack was the largest on Moscow in at least two years, Russia's state TASS news agency reported.And the second time this month that Kyiv has launched a major attack during an international summit after striking Saint Petersburg at the start of a landmark economic forum near the city.All of Moscow's airports were shut for hours, leading to hundreds of flight delays.The country's busiest -- Sheremetyevo -- announced it had evacuated passengers to "safe locations" during the barrage, before it re-opened at around 11:00 am (0800 GMT)."Several drones managed to reach the MNPZ (Moscow Oil Refinery)," Moscow Mayor Sergei Sobyanin wrote on Telegram early Thursday, without specifying damage to the facility.