Former England rugby player Tom Voyce is believed to have died after apparently trying to cross a flood-swollen river in his car.
Northumbria Police said the 43-year-old is believed to have gone into the River Aln near Alnwick, Northumberland, which was hit by heavy rain during Storm Darragh.
Officers are searching for Mr Voyce, who has not been seen since Saturday.
A force spokesperson said: "At this time, it is suspected Tom has attempted to cross Abberwick Ford in his car, which has then been pulled along with the current of the river.
"Officers have since recovered his car, but sadly Tom is yet to be found.
"It is believed in his attempts to escape he has been swept away and tragically died."
Voyce won nine caps for England during his career and spent six years at Wasps, from 2003 to 2009, where he helped them win European and domestic titles, moving there from Bath and then leaving to join Gloucester in 2009. He made a total of 220 Premiership appearances before retiring in May 2013.
A post on X from the England team's account read: "Our thoughts and prayers are with the family and friends of Tom Voyce at this extremely challenging time."
Gloucester posted that they were "desperately sad to hear the distressing news regarding our former player and friend, Tom Voyce", adding: "Our thoughts and prayers go out to Tom's family and friends at this incredibly difficult time."
Bath echoed those messages by posting: "Our thoughts and prayers are with the family and friends of Tom Voyce at this incredibly distressing time."
Police received a report on Sunday morning that Mr Voyce, who played at wing or fullback during his career, had not returned to his home following an evening with friends.
Chief Superintendent Helena Barron, from Northumbria Police, said: "This is an extremely tragic incident, and our thoughts are very much with Tom's loved ones at this time.
"Our officers continue to support his family and we would ask that their privacy is respected.
"Extensive enquiries have been ongoing since concerns were raised for Tom, including deploying specialist teams to search for him."
The search has included specialist officers from the force's Marine Section, the National Police Air Service, drones and dog handlers.
Volunteers from the North of Tyne Mountain Rescue have also been searching alongside Mr Voyce's family and friends.
Chief Supt Barron added: "Our searches continue but we are dealing with very challenging circumstances in trying to recover Tom.
"This is down to the conditions, including the river flow and the level being significantly heightened due to the exceptionally heavy rain we experienced over the weekend.
"Sadly, we can therefore not provide any timescales around this.
"We would like to thank our colleagues from Mountain Rescue for their continued support and all those who have helped with the searches."
Those who have been carrying out the searches have been doing so in a co-ordinated manner and are either trained or know the local area and terrain well.
Members of the public are asked not to attend the scene to conduct their own searches.
The spokesperson said Mr Voyce's wife Anna and all his family have expressed their gratitude for all the help and support from the police, friends and the local community in helping find Tom.
A Northumberland Fire and Rescue Service (NFRS) spokesperson said they were called to the scene at 2.10pm on Sunday by Northumbria Police.
"We attended with our Swift Water Team and provided portable lighting units to assist the search," they said.
"Our teams also secured the car to the bankside.
"NFRS has since been stood down by the police.
"Our thoughts are with the family and friends of the missing person at this incredibly difficult time."
