Seventeen apartment buildings were evacuated on Saturday in a Russian town near the Ukrainian border after an explosive device was found at the site where a bomb accidentally dropped by a Russian warplane caused a powerful explosion this week, authorities said. .

The bomb blast on Thursday night rocked part of Belgorod, leaving a large crater and injuring three people. The Russian Defense Ministry was quick to acknowledge that a weapon accidentally dropped by one of its own Su-34 bombers caused the explosion.

The ministry said an investigation was underway, but gave no further details about the weapon, which military experts said was likely a powerful 1,100-pound bomb.

The governor of the Belgorod province, Vyacheslav Gladkov, reported on Saturday that the sappers who examined the site of the explosion on Thursday found and decided to detonate what he called an «explosive object» that was «in the immediate vicinity of residential buildings.»

Preventive evacuations ended later that day, according to Belgorod Mayor Valentin Demidov.

“The bomb was removed from the residential area. Residents are being returned to their homes,” Demidov wrote on Telegram.

Russian authorities did not say whether the detonated device was accidentally dumped on Thursday and, if so, whether it was a remnant or separate from the bomb that exploded in the city.

Belgorod, located about 40 kilometers (25 miles) east of the Russia-Ukraine border, has faced regular drone strikes since Russia sent troops to Ukraine last year. The Russian authorities have blamed those attacks on the Ukrainian military, which refrained from directly claiming responsibility for the attacks.

Moscow’s invasion of Ukraine has deeply frozen relations with the West, with frequent expulsions of diplomats from both sides.

On Saturday, the Russian Foreign Ministry said German authorities had «decided on another mass expulsion of employees of Russian diplomatic missions in Germany.» He said that Moscow would expel the German diplomats in response.

A ministry statement said that «as a reaction to hostile actions from Berlin,» Russia decided to «mirror» the expulsions from Germany and «significantly limit» the maximum number of staff in German diplomatic missions in Russia.

The German Foreign Ministry said it took note of the comments. He said the German government and Russia had been in contact in recent weeks over «issues about the staffing of the respective diplomatic missions» and that a flight on Saturday took place in that context. He did not give further details.

The German air force said earlier that a Russian plane flew to Berlin with diplomatic clearance on Saturday, but did not specify who or what was on board. Special authorization is required because the European Union closed its airspace to Russian planes shortly after the war in Ukraine began.