Shortly after the suspect dropped the parcel, the device detonated, ripping through the building in the micro-state’s quiet and luxurious La Rousse district.
Silvano Ippolito, a resident of Monaco who lives nearby, told France’s BFMTV television station that he at first suspected a gas leak.
Then he saw “a woman slumped over and covered in blood” on the stairs of the house, along with “a little boy who was bleeding on the ground with a person who was trying to help him”.
“She was missing her feet,” Mr Ippolito said.
Footage circulating on social media showed several firefighters carrying a person on a stretcher as sirens blared. The person’s condition was unclear.
Four additional people went to Princess Grace Hospital, including two with cuts from windows that shattered and two others who needed treatment for shock, the Monegasque government said.
Tycoon sanctioned by Kyiv
Mr Ermolaev, who obtained Cypriot nationality in 2019 and renounced his Ukrainian citizenship, relocated to Monaco just after the start of Russia’s invasion of Ukraine, a source close to the investigation told Le Figaro.
The oligarch, 58, built his wealth in real estate. In 2001, he founded Alef Estate, which specialises in office, retail and residential buildings in Dnipro, a city that has come under heavy fire since Vladimir Putin launched his war.
However, in recent years Mr Ermolaev fell foul of Ukraine’s government. In 2023, he was sanctioned by Kyiv for selling alcohol in Russian-occupied Crimea.
According to the national security and defence council of Ukraine, which operates a register of sanctioned individuals, the penalties on Mr Ermolaev include asset freezes and trading restrictions within the country.
Mr Mirmand said during a press conference on Monday that intelligence services were investigating the victims’ background and would “determine if others might be facing specific threats”.