A manhunt is under way in southern France after a parcel bomb exploded at a residential building in neighbouring Monaco, severely injuring a wealthy Ukrainian businessman and two others.

Vadym Yermolaiev and two others are believed to have been injured in the attack, according to French media reports. The victims’ identities have not been officially announced by authorities.

Two of the victims are in a critical condition in hospital in Nice, Monaco’s public prosecutor Stéphane Thibault said, adding that the woman was most seriously hurt.

The blast occurred shortly before 21:00 local time (19:00 GMT) at an apartment building on Rue Révérend Père Louis Frolla, near the border with France.

Monaco’s government said the explosion was caused by a parcel bomb, while the Minister of State of Monaco Christophe Mirmand told AFP news agency the explosive device appeared to contain bolts and pellets.

Speaking at a news conference on Tuesday, Thibault said that two others were injured by debris from nearby shop windows as a result of the blast.

He said authorities were searching for a single suspect and that the incident was not being categorised as a terrorist attack.

On Tuesday morning, Mirmand told French broadcaster BFM TV the suspect “appears to have left for France”.

The Monaco government has said a suspect was seen on a video surveillance system fleeing towards the French commune of Beausoleil on foot after the explosion, where a major police effort to find them is now taking place.

Video surveillance images of the moments before the attack showed a man dropping a backpack in the lobby of a building shortly before the explosion, French newspaper Le Figaro reported.

More than 100 police and emergency personnel were deployed to the scene of the blast on Monday evening.

Harri Richie, who lives around 100m away from the targeted building, told the BBC she heard an “unbelievably loud explosion” at about 21:00 local time from the underground car park she was in.

She then went up to her 11th floor apartment, where she said she saw emergency services “dragging two people out [from the building] who looked badly injured”.

Emergency services arrived around five minutes after the explosion, she said, adding that there was a helicopter overhead throughout Monday night.

“This is the first time in history, to my knowledge, that such an act has taken place in the principality,” Mirmand, the head of Monaco’s government, said.

Monaco’s Prince Albert II described the incident as a “heinous crime” and “a shock to the entire Monaco community”.

Citing anonymous sources, French newspaper Le Figaro reports that the three victims seriously hurt in the attack are Yermolaiev, his partner and their 13-year-old son.

Yermolaiev is a 58-year-old wealthy real estate developer from Dnipro, Ukraine’s fourth-largest city, who has been living in Monaco.

He is now a Cypriot citizen after renouncing his Ukrainian citizenship in 2019.

He has big interests in the wine and alcohol business in Russian-annexed Crimea, and since 2023 has been the subject of sanctions imposed by the government in Kyiv.

He was named the 39th richest Ukrainian by Forbes magazine in 2020, with a fortune of $230m (£173.8m).