A child is missing and two others have been rescued after getting into difficulty in Westport Lake in Stoke-on-Trent.
Emergency services began their search in the water following reports the three children were in distress.
Staffordshire Police said they were called to the scene at around 4.50pm on Monday.
Two of the children made it safely out of the lake, but one is still missing.
Emergency services including West Midlands Ambulance Service, Staffordshire Fire and Rescue Service, Staffordshire Air Ambulance and the National Police Air Service are all in attendance.
A police cordon is in place.
The identities of the children are known to officers who are in contact with the parents.
Anyone with information is asked to call 101 urgently quoting incident 629 of 25 June.