A 15-year-old boy went missing after getting into difficulty while swimming with friends in a river yesterday.
Emergency services rushed to the scene after receiving reports of four teenagers in trouble in the River Eden near Warwick Road, in Carlisle, at 6.41pm on Friday evening.
After Cumbria Fire and Rescue Service arrived, a 14-year-old boy was airlifted to hospital in a critical condition and two other teenagers had to be checked over by medical professionals.
One of those two teenagers was able to swim to safety while the other was rescued by a member of the public.
But the fire service confirmed a 15-year-old boy was missing after getting into difficulty and the river was today continuing to be searched by teams.
Emergency services were called to the area around Rickerby Park and it is understood that a coastguard helicopter has also been involved in the search.
A spokesman for Cumbria Fire and Rescue Service said: "At 6:41pm today (26 May), Cumbria Fire and Rescue Service were called to the River Eden, Carlisle regarding four teenage males that were reported to have got into difficulty in the river.
"One male, aged 15, remains missing as agencies continue their efforts to locate him.
"The operation is being supported by a number of search and rescue teams. One male, aged 14, has been airlifted to hospital in a critical condition.
"One of the group managed to swim to safety, while another was rescued safely by a member of the public. Both have been checked over by medical professionals."
Last Wednesday evening, a body believed to be of a 16-year-old boy was recovered from the River Calder in Castleford, West Yorkshire.
While also last Wednesday - as the UK enjoyed a scorching day - saw a double tragedy involving two men aged 19 and 18 at High Eske Nature Reserve, in Tickton, East Yorkshire.
That prompted Humberside Fire and Rescue Service to stress the deadly dangers of open water in hot weather and how treacherous it can be.
They went on: "The service would like to stress the importance of remaining safe around open water and the clear advice from the emergency services is that people should not enter the water.
"Open water such as ponds, rivers and lakes etc are highly dangerous and people should not enter them."