A 12-year-old Belleville, Ont., boy is in serious condition in a Kingston Hospital after he was struck by a boat while swimming in the water at a summer camp.

Ontario Provincial Police said the boy was part of a day camp group playing Wednesday just before 5 p.m. at a beach at North Beach Provincial Park, about 20 kilometres south of Trenton, Ont.

He was swimming in North Bay, an inland lake close to Lake Ontario, and had finished a tube ride moments before he was struck.

A power boat operated by a 19-year-old camp counsellor from London, Ont., was pulling another boy when it struck the swimmer.

The boy was hit by the propellor and suffered serious injuries, including lacerations, to his chest, according to OPP Const. Kim Guthrie.

Witnesses administered first aid until paramedics arrived and took him to Trenton Hospital. He was later transfered to Kingston General Hospital where he remains in serious condition.

Pleasant Bay Children's Camp confirmed the boy was one of more than 40 children attending the camp this week. A camp spokesman said the teen driving the boat was licensed to operate the vehicle.

OPP are investigating the incident.