RENFREW, Ont. -- A search is underway for a 20-year-old swimmer after police say he was swept away by rapids in the Ottawa River.

Ontario Provincial Police say divers and a helicopter were still searching for the man on Saturday morning after he failed to return to shore the night before.

They say he and another man were caught in rapids while swimming near Renfrew, Ont., in the Ottawa Valley on Friday evening.

Police say the other swimmer managed to make it back to shore and called for help.

They say emergency workers were assisted by two infrared-equipped helicopters in their initial search for the man, but he could not be found.

They say they will provide updates as the search effort continues.