Russian ballistic missiles slammed into an apartment block in Kharkiv and killed at least four people in a night-time attack, Ukrainian officials said Friday, a day after US President Joe Biden gave Kyiv a green light to strike back with American weapons at Russian military assets targeting the city.

Russia launched five S-300/S-400 ballistic missiles at Kharkiv overnight, Ukraine’s air force said. One of them struck a residential building close to midnight and was followed by another missile 25 minutes later that hit first responders, officials said.