A 15-year-old boy is believed to have drowned in a river at a country park.
The teenager was airlifted to hospital by police helicopter after the incident in the Roe Valley Country Park near Limavady in County Londonderry, on Thursday afternoon, the Police Service of Northern Ireland said.
A police spokeswoman said: "Police and other emergency services were called to the park at around 4.30pm. The teenager is believed to have drowned after falling into the River Roe."
The force had no further details, she added.
Stormont's Environment Minister Mark H Durkan expressed his sympathy to the family of the teenager who died, saying he had ordered a report into the incident.
Roe Valley Country Park is managed by the Northern Ireland Environment Agency.
"This is a terrible tragedy," said the minister.
"My heart goes out to the family of the teenager and I offer them and his friends my deepest sympathy.
"Given that DOE manages Roe Valley Country Park I have asked my officials for an urgent report on this tragic incident.
"I cannot advise people strongly enough of how dangerous rivers, reservoirs and quarries are and my clear message is 'stay out of the water and stay safe'. "