A combined Russian missile and drone attack on Ukraine overnight killed at least 15 people — including an American citizen — and wounded scores of others, according to Ukrainian officials.

President Volodymyr Zelenskiy said on Friday that Ukraine was working on the rapid development of interceptor drones to counter the swarms of Russian drones that have been descending on Ukrainian cities in increasing numbers in recent weeks.

Russia launched 315 drones at Ukraine overnight into Tuesday, in what Ukrainian President Volodymyr Zelensky said was “one of the largest” attacks on the capital Kyiv, with local officials in the southern port city of Odesa also reporting a maternity ward there had been hit.