A Russian fighter jet mistakenly dropped a bomb on a city in southwestern Russia, killing at least 12 people and injuring dozens more, the Russian Defense Ministry said on Friday.

The incident occurred on Thursday evening, when an SU-34 air force plane had an “accidental discharge” of its weapons during a training flight over the Belgorod region, which borders Ukraine, the ministry said in a statement.

The bomb hit a residential area in the city of Belgorod, causing a large explosion and a fire that damaged several buildings and vehicles. The blast also shattered windows and knocked out power in nearby homes and businesses.

The ministry said it had launched an investigation into the cause of the accident and expressed its condolences to the victims and their families. It also said it would provide compensation and assistance to those affected by the bombing.

According to his spokesman, Dmitry Peskov, Russian President Vladimir Putin ordered a thorough probe into the incident and instructed the defense minister to take measures to prevent such accidents in the future.

The bombing of Belgorod raised questions about the safety and readiness of Russia’s military, which has been involved in a tense standoff with Ukraine and NATO over the conflict in eastern Ukraine and the annexation of Crimea.

Russia has deployed thousands of troops and military equipment along its border with Ukraine in recent weeks, sparking fears of a possible invasion or escalation of hostilities. Russia says it is conducting routine exercises and has no intention of attacking its neighbor.

However, some analysts have warned that the buildup of forces could increase the risk of accidental clashes or miscalculations that could trigger a wider war. The bombing of Belgorod could be seen as an example of such a risk, they said.

“This is a tragic reminder that military operations are inherently dangerous and unpredictable,” said Pavel Felgenhauer, a Russian defense analyst and columnist for Novaya Gazeta. “It shows that Russia’s air force is not as well-trained or disciplined as it claims to be.”

He added that the incident could also have diplomatic repercussions, as it could undermine Russia’s credibility and image in the international arena.

“It’s a huge embarrassment for Russia and a blow to its prestige,” he said. “It could also raise questions about Russia’s compliance with international treaties and norms on arms control and civilian protection.”