A dangerous new Facebook craze has left a young man dead and another severely injured.
The craze has been spreading across France as people challenging friends to jump fully clothed into rivers and the sea and film the stunt.
Police said a 19-year-old drowned after driving his bicycle into a river in a town in western Brittany while a friend filmed him. Police said the man was dragged under the water by his bike.
Police chief Colonel Sylvain Laniel said: "The young man drowned after being thrown into the water with his bicycle as part of a challenge.
"The victim had seen fit to tie his bike to his leg to recover, but there were six-metres deep and could not go back."
Mr Souchu added: "The victim repeatedly attempted to resurface but could not because of the weight of the bike."
Another youth suffered serious injuries after diving headfirst into shallow water near Calais.
Deputy prosecutor Igor Souchu criticised the "dramatic and stupid" game after the death in Beganne.
Police have posted a warning on Facebook saying: "Don't be influenced by a stupid phenomenon of the moment."
The latest social media craze follows the global spread of the Neknomination craze - an online drinking game in which people filmed themselves drinking dangerous amounts of alcohol before nominating friends to do the same.
20-year-old Bradley Eames became the fifth victim to die as a consequence of Neknominate.
After the trend lead to several deaths, lawyers warned that those issuing the challenges may be liable for prosecution under charges of manslaughter.