Police are investigating reports that a man plunged from the Foyle Bridge in Derry on Monday morning.
Search and rescue and the PSNI have been combing the area.
A PSNI spokesman confirmed that the force received a report that somebody had jumped into the Foyle River.
Separately, the search for missing Dublin teenager Kieran McKeon at the River Foyle has entered its fifth day.
The 18-year-old was last seen in a hotel in Londonderry last Thursday morning, with his friend Alexandra O'Brien.
She was described as a vulnerable woman, and had travelled to Derry after she checked out of a hospital in Dublin.
The 21-year-old's body was recovered from the Foyle on Thursday.