KYIV, UKRAINE (AP) — Ukraine’s capital region was struck by Iranian-made kamikaze drones early Thursday morning, sending rescue workers rushing to the scene as residents awoke to air raid sirens for the fourth morning in a row following Russia’s massive, deadly assault across the country on Monday.

Kyiv regional governor Oleksiy Kuleba said the strike occurred in the area around the capital city. It was not yet clear if there were any casualties.

In the southern city of Mykolaiv, overnight shelling destroyed a five-story apartment building as fighting continued along Ukraine’s southern front.

Mykolaiv Mayor Oleksandr Sienkovych said the building’s top two floors were completely destroyed in a single strike and the rest of the building was left in rubble. It was not immediately clear if there were any casualties.