"Four drones have exploded so far — one in the port, one near the port at about 11 a.m., and two on the Ukrainian side," the sources said, without providing additional details.
Constanța County Prefect Adrian Picoiu told reporters that a drone similar to the one that exploded in Constanța had been destroyed in international waters and that "there may be three more that have gone missing."
He said the drone that exploded was likely of Ukrainian origin, although that has yet to be confirmed.
Later, European Pravda reported that the Romanian government had confirmed media reports about four maritime drones in the Black Sea.
Explosion of a maritime drone in a Romanian port
A maritime drone exploded in Romania's port of Constanța on June 5. Romania's Ministry of National Defence said the drone may have been Ukrainian. The ministry added that the drone self-destructed.
Commenting on the explosion of the uncrewed vessel in the port and the recent crash of a Russian drone into a residential building in Galați, Romanian President Nicușor Dan said such incidents were direct consequences of Russia's war against Ukraine.
"Given the military conflict on our border, it is obvious that the security environment we are living in is sensitive, and we will maintain a high level of vigilance. Such particularly serious situations are direct consequences of the aggressive war launched by Russia against Ukraine," he wrote on X.
European Commission President Ursula von der Leyen also said the incidents were consequences of Russia's war against Ukraine.
"One week after a drone struck an apartment building in Galați, a maritime drone reached the port of Constanța today. This is a direct consequence of Russia's war against Ukraine. It is increasingly becoming a direct threat to countries on our eastern border," she wrote on X.
Von der Leyen said the European Union stands in full solidarity with every member state facing such threats and stressed that the response must match the urgency of the situation.
Later, the Ukrainian Navy said a Ukrainian maritime drone had drifted into Romanian waters after losing control as a result of Russian electronic warfare interference.