June 30 (UPI) — A Ukrainian construction mogul and his partner and 13-year-old son were seriously injured after a parcel bomb detonated in a residential building in Monaco.

The Monaco government said in a statement posted online in the early hours that “a violent explosion linked to a booby-trapped package was heard in the Principality” close to the main Place des Moulins residential district.

Vadym Yermolaiev, 58, a native of Dnipro, was the likely target of the attack which occurred just before 9 p.m. local time on Monday, about 1.5 miles northeast of the Prince’s Palace, close to the border with France, authorities said.

Yermolaiev, his wife and son were taken to hospital across the border in Nice where the two adults were reported to be in critical condition. Four other people were being treated for injuries from flying glass and for shock.

Monaco government spokesman Manuel Vitali said an investigation had been launched by the attorney general.

CCTV from the scene showed a man leaving a backpack in the building’s lobby shortly before the blast, according to Ukraine’s RBC, while the Monaco government said security cameras captured a suspect headed toward the French town of Beausoleil on foot.

Vowing that the principality would “remain united and resolute in the face of violence and crime,” Prince Albert II of Monaco said in a post on Facebook that all relevant state services had been mobilized to deal with the situation and were working closely with the authorities in France.

More than 100 police and emergency workers, including firefighters from across the border, raced to the scene on Rue Reverend Pere Louis Frolla, according to the government.

Photos showed the bombed-out entrance and lobby of the building with debris strewn across the street and at least one first-floor room with its windows blown out.

Yermolaiev, who made his fortune — which Forbes magazine put at $220 million in 2021 — in real estate, construction and trading, was born in Dnipro but moved overseas about four years ago after obtaining Cypriot nationality in 2019.

Ukrainska Pravda said he was among a group of Ukrainian businessmen, politicians and oligarchs dubbed the “Monaco Battalion” who resettled along the French Riviera when Russia launched its full scale invasion of Ukraine in February 2022.

Ukraine imposed personal sanctions on Yermolaiev in December 2023 following a National Security and Defense Council ruling on alleged tax payments made to Moscow by his alcohol business concerns in occupied Crimea.