An inquiry is being carried out by police following a report someone had entered the River Wear in the early hours of today.
Sunderland Coastguard Rescue Team joined colleagues from Seaham and Sunderland's RNLI Inshore and Atlantic Lifeboats at 6.30am today after a call a person had possibly entered the river wound the Wearmouth Bridge.
The report said a woman was in the water underneath the bridge, with the search stood down when further information was received.
A spokesman for the Coastguard said: "After a search involving both Coastguard teams, lifeboats and police helicopter, all units were stood down with nothing untoward having been found.
"It is understood that Northumbria Police are making further enquiries to validate the authenticity of the report."
It added coastal emergencies should be reported to the Coastguard via 999.
The Samaritans can be called on 116 123 or by emailing email@example.com.
The two Coastguard teams received a further report as they left the scene, relaying information that flashing lights had been seen around 3 miles out to sea.
Sunderland's officers headed to Hendon, while Seaham's went to Ryhope.
After speaking to fishermen and searching the coastline, no vessels appeared in distress the the teams were stood down.