The Waterford Coastguard helicopter and the Garda Sub Aqua unit, assisted by Kilkenny River Rescue personnel, are this morning searching for a man who entered the River Nore in Waterford last night.
It is understood the missing man was walking along the riverbank with friends when he entered the water for reasons yet unclear.
The alarm was raised at around 1:30am and the Waterford Coastguard helicopter attended the scene, but returned to base at around 7:00am.
The search resumed earlier this morning.