The emergency services were called to a party hotspot in Deurne (Antwerp) on Saturday morning after three scout leaders aged between 20 and 24 were attacked by a group of about 15 youngsters.
A police spokesman said: “The victims stated that they received countless blows. It’s likely bike helmets were used too.”
One of the victims was taken to intensive care. The attackers were aged between 16 and 18. Antwerp police are now trying to identify them.
A police spokesman said: “We support the appeal for witnesses made by the scout group. Anybody who was present at the party should certainly report this to the police. All information on the attackers is welcome.”