Police in County Derry say a man seen getting into difficulty in the River Bann near Kilrea at about 6 o'clock yesterday evening, is a 21 year old from the Ballymena area.
Rescue teams have this morning resumed their search for the man around the Bann Road bridge area of the river.
Three men aged 25, 26 and 30 have been arrested and are helping police with their inquiries.
East Derry MLA John Dallat says it seems that the man entered the river as an act of desperation.
He says as the mystery of last night unfolds, it is imperative that the community plays its part in helping the police uncover the truth behind this deeply distressing event.