Romania said ​on Friday that a drone injured two people in a southeastern city during an overnight Russian attack on neighboring Ukraine, the ‌first time in the conflict that a drone had hit a densely populated area in Romania and caused injuries.

The incident in Romania, a member of the North Atlantic Treaty Organization (NATO) and the European Union (EU), was likely to increase tensions on NATO's eastern flank at a time when Ukraine's allies are worried about the conflict spilling over and spreading.

The drone hit the roof ​of a 10-story apartment building in Galati, a city in eastern Romania near the Ukrainian border, and caused an explosion, the authorities said.

A fire broke out in a 10th-floor apartment after ‌the drone ⁠struck the building's roof and exploded, Romania's emergency response agency said. Two people were receiving medical treatment on site, it said, adding that 70 people had evacuated.

The drone's entire explosive payload detonated, and the fire was extinguished, the emergency agency said.

Romania, which shares a 650-kilometer land border with Ukraine, ​has experienced Russian drones breaching its airspace 28 times since Moscow began attacking Kyiv's ports across the Danube river, Romania's ⁠defense ministry said.

The ministry said it had recovered drone fragments that fell in Romania 47 times.

"Romania will take the ​necessary diplomatic measures in response to this serious violation of international law and its airspace," Romanian Foreign Minister Oana Toiu said on X.

Russia's defense ministry did not immediately comment on the incident.

(With input from Reuters)