An explosion at a residential building in Monaco on Monday evening left three people seriously injured, two of them in life-threatening condition, in what the principality’s government described as a deliberate act. The blast occurred around 9 p.m. local time at the entrance of a building on Rue du Révérend Père Louis Frolla, near the French border, according to Monegasque authorities.

Medical sources in Nice, where the wounded were taken, said a couple in their 50s or 60s were in critical condition, while a 13-year-old boy sustained less severe injuries. French and Ukrainian media, citing sources close to the investigation, identified the man as Vadim Ermolaev, a Ukrainian-born businessman who has resided in Monaco since the start of the war in Ukraine. The woman and the teenager are believed to be his partner and son. Monegasque officials have not publicly confirmed the identities, but a source familiar with the inquiry told Agence France-Presse that Ermolaev was among the victims.

Surveillance footage showed a man leaving a backpack or bag at the building’s entrance moments before the explosion, then walking away towards the French commune of Beausoleil, according to Monaco’s prosecutor general. A joint search involving French and Monegasque police is under way; the suspect remains at large. The device, which authorities said contained bolts and buckshot, detonated as other people were entering the building, though it is unclear whether they were the intended target.

Ermolaev, 58, is the founder of the Alef industrial and real-estate group and was once listed among Ukraine’s wealthiest individuals. He renounced Ukrainian citizenship in 2019 and now holds a Cypriot passport. In December 2023, President Volodymyr Zelensky imposed personal sanctions on him, a decision Ukrainian security services linked to his continued alcohol-trading operations in Russian-occupied Crimea. Ermolaev has challenged the sanctions in court, arguing that his Crimean assets were seized by Russian authorities and that he condemns the invasion. Russian-language outlets, citing Ukrainian bloggers, have speculated that the explosion may be connected to a dispute with Ukrainian intelligence or to his son’s criminal conviction in Estonia for running fraudulent call centres, but no evidence has been presented to support these claims.

Prince Albert II called the explosion “an odious crime” and a shock to the Monegasque community, while Minister of State Christophe Mirmand said it was “very likely an attack” and the first such act in the principality’s history. Security has been reinforced, and authorities are working with intelligence services to determine whether other individuals might be at risk. The investigation is ongoing, and no motive has been established.