A search is underway for a missing boy who vanished after going swimming in a river on Saturday.
The teen entered the River Eden in Rickerby Park near Stony Holme, Carlisle, yesterday and has not been seen since.
Officers have asked the public to avoid the area to enable police to conduct searches.
Locals had flocked to the popular swimming spot on Saturday, with temperatures reaching 30C.
It comes after swimmers were warned that rivers and lakes are more dangerous this year because water temperatures are lower than normal.
At some swimming spots water is as cold as 10C. Entering water this cold suddenly increases the risk of people suffering from cold water shock.
Ross MacLeod, the Royal National Lifeboat Institution (RNLI) water safety manager, told the Sunday Telegraph that swimmers should enter the water "slowly and acclimatise".
He said people who may accidentally inhale water after jumping in could drown or undergo a sudden cardiac arrest.
“If you jump in the water, such as tombstoning, that gasp response can lead to drowning very quickly - you hear horror stories of people never resurfacing,” he said.
On average, 400 people drown each year in Britain. Thirty teenagers and children died in the water last year alone.
Cumbria Police and North West Ambulance Service have been approached for comment.