Rescue crews were scrambled after reports came in that a person had fallen from Wearmouth Bridge in Sunderland.
The city's Coastguard Rescue team were called out to the incident last night after a member of the public said they had heard a "large splash" in the water.
A lifeboat was used to search the River Wear below, with volunteers from South Shields Volunteer Life Brigade assisting.
However no-one was found and the teams were later stood down.
It is now believed that the splash was caused by items from roadworks currently on the bridge being thrown into the water.
A statement on the organisation's Facebook page posted late last night said that the team were called out shortly before 10pm
It read: "Coastguard officers from Sunderland were paged this evening to a multi agency incident under the Wearmouth Bridge after reports a person had possibly fallen from the Bridge.
"Concerns were raised after members of the public under the bridge had heard a large splash but hadnt witnessed what had fallen.
"A extensive shore based search was carried out by ourselves and South Shields Volunteer Life Brigade (SSVLB) whilst the lifeboat from Sunderland searched the river.
"With nothing found between the bridge and the Fish Quay and no signs of anyone in distress all the teams were stood down.
"It's believed the splash had been caused by items from the roadworks on the bridge being thrown into the water.
"False alarm with good intent."