The 16 year olds got into difficulty in Enagh Lough in Londonderry on Monday night.
Two 16-year-old boys have died after getting into difficulty at Enagh Lough, close to Londonderry.
Emergency services were called to Temple Road at about 18:30 BST on Monday.
One of the boys was taken from the water and transferred to hospital, where he was later pronounced dead.
The second boy was pronounced dead at the scene after being recovered from the water after searches by Foyle Search and Rescue and police divers.
Police said another boy was taken to hospital for treatment to injuries, which are not believed to be life threatening.
Three other boys were also at the scene.
“While they have been left shocked, are not physically injured”, Insp Brogan said.
“Enquiries are ongoing into this incident, but we believe, at this stage, that this was a tragic drowning incident.
“Our thoughts are with the families of those affected,” he added.
Waterside parish priest Father Michael Canny said the tragedy would be felt all over the city.
He said the families were traumatised and absolutely devastated.
“They are part of the Indian Kerala community who worship here at St Columb’s in Waterside,” he said.
“The boys are at a local grammar school and two of the mothers are nurses, I understand. Another works in the health service and another is a local in business here.”
“It’s an awful tragedy and there is tremendous sadness all round”.
Signs of tragedy remain at lough
BBC Radio Foyle’s Anna Maguire, at the scene
Yesterday was a balmy blissful end of summer day.
But at this lough – where six young men came to bathe in the water – a tragedy unfolded.
The lough, quite a big lough, is now completely still and clear.
Six bikes are still here, propped up against trees, a bank and a fence, leading to a small jetty that leads out onto the lough.
There are a number of pairs of shoes, jackets and rucksacks, all the signs of youngsters who came down to the water on a warm bank holiday evening.
SDLP assembly member Mark Durkan said it was an “absolute tragedy”.
Mr Durkan said he understood a group of boys went out for a cycle in the area and a couple of them went for a swim in the lough.
“It’s my understanding from talking to some of the boys that one of them got into difficulty in the water,” he said.
“His friend tried to help him and he ended up in equal difficulty.
Democratic Unionist Party assembly member Gary Middleton described it as a devastating tragedy and said his thoughts and prayers were with the victims’ families.
Sinn Féin assembly member Ciara Ferguson said the thoughts and prayers of everyone in Derry were with the families.
Alliance councillor Rachael Ferguson said the community had been shocked and saddened.
“I spoke to some of the family members who were just in shock and the young boys I saw – it’s just devastating what they witnessed,” she said.
“They are going to need a lot of support”.
‘Tragic outcome’
Northern Ireland Ambulance Service medical director Dr Nigel Ruddell told BBC Radio Foyle that a number of specialist crews including the helicopter emergency medical service had attended the incident.
Initially, he said, ambulance crews responded to reports of two people missing in the water.
“There were others who had been in the water, one of whom was taken to hospital suffering the effects of having been in the water, but mercifully is doing well,” he said.
“Unfortunately one individual was removed from the water in a very serious condition and transported to Altnagelvin [hospital].
“Then there was regrettably a prolonged search to try to locate another young man who had been reported missing.
“It turned into quite a lengthy operation, and regrettably with a tragic outcome. Our thoughts this morning are with those directly involved and their family and their friends in these tragic circumstances”.