Steven Mitchell was teenager who died in River Roe
The 15-year-old boy who died after going into the River Roe near Limavady in County Londonderry was Steven Mitchell from Doagh, County Antrim.
The emergency services were called to the Roe Valley Country Park at about 16:30 BST on Thursday.
It is understood he went into the water to retrieve a ball, but got into difficulties.
Emergency services arrived and a helicopter airlifted him to Altnagelvin Hospital from an adjacent field.
However, it is believed he may have been in the water for some time and did not survive.
The part of the river where the incident happened is known as Givens weir and is accessible by foot only.
Environment Minister Mark H Durkan said the boy's death was a "terrible tragedy" and that he had asked his officials for an urgent report on the incident.
"My heart goes out to the family of the teenager and I offer them and his friends my deepest sympathy," he added.