Kiev came under drone attack on Tuesday after the expiration of a three-day truce with Russia, according to Ukrainian authorities.
"Enemy UAVs are currently over Kiev. Please stay safe until the alert is cleared," the head of the capital's military administration, Tymur Tkachenko posted on Telegram.
The alert siren was the first confirmed in the capital since Friday, before the ceasefire came into force.
Kiev's regional military administration told residents to remain in shelters and said its air defences could be operating in the area.
A three-day truce was announced on Friday by US President Donald Trump, just hours before Russia's World War II victory celebrations, with Trump saying he hoped the ceasefire would mark "the beginning of the end" of the conflict.
The two countries had traded accusations of attacks on civilians that violated the truce, which Trump had said would be in place between May 9-11.
