Scores of university students have joined water rescue professionals as the search for teenager Euan Coulthard stretches into its third day.
Police say their "concerns are rising" for the 19-year-old but they remain hopeful he will be found safe and well.
The law student from Durham University's St Mary's College has not been seen or heard from since shortly before midnight on Wednesday, when CCTV captured him crossing the pedestrian Framwellgate Bridge alone. Police have established that his mobile phone powered down several minutes later.
On Saturday around 100 fellow students continued to work alongside professional rescue teams as searchers began to scour the fast-flowing River Wear below. Its waters reached about one metre higher than usual earlier this week.
"Because the river has been so high, today, Saturday, has actually been the first opportunity we've got to actually search the river as well as the banks," Chief Inspector Sue Robinson told Sky News.
"Of course as time passes, and we've had tremendously cold weather over the last three days, the welfare of Euan is paramount and our concerns are rising. However, this is still an active missing from home inquiry, and we'll continue in that vein until we receive information otherwise."
She said she had "every hope" Mr Coulthard would still be found.
It is expected the search will be called off at sunset but will resume at first light on Sunday.
Mr Coulthard is 5ft 9in, of average build, with light brown hair, which is short on the sides and longer on the top. When last seen he was wearing black skinny jeans, a denim jacket and a beige patterned shirt.
He'd been out celebrating a friend's 21st birthday at an Italian restaurant, and went on to the Love Shack nightclub.