A southwest Sydney school says it is deeply saddened by the death of a student who lost his life after falling 15 metres into a swimming hole.
Amir Ammari, 16, fell and hit his head on a submerged rock after the tree branch he was swinging on snapped at Kellys Falls, near Helensburgh in Sydney's south, about 1.30pm on Wednesday, police say.
"He has gone out on the branch itself, which is hanging over the water ... and it snapped, so he has plummeted about 10 to 15 metres," Detective Inspector Brad Ainsworth told AAP.
The teenager was knocked unconscious and he was dragged from the water by his three friends.
Amir was winched out by helicopter and flown to Royal North Shore Hospital in a critical condition but died on Wednesday night.
The 16-year-old was a student at Robert Townson High School in Campbelltown, which released a statement on Thursday.
"Our thoughts are with the student's family and friends at such a difficult time," the school said.
"Counselling has been provided to students and staff and will continue to be available as necessary."
Images posted on social media on Thursday show students releasing pink and purple balloons at the school, and gathering hand-in-hand near a makeshift memorial of photographs and flowers.
"Together we stand as one. We unite as one. We pray that God takes care of our beautiful angel who was taken away from us on the 22/02/2017. Today you fly high. We love you Amir Ammari," student Mariman Jawar said in a Facebook post.
Friend Leilani Rapana said: "It's just a sad thing that the homeboy was chosen! Rest easy."
"Man you had a lot to live for bro," Monty Paea added.
Curiously, Amir captioned his most recent Facebook picture: "Born to die may as well live".
Police said a paramedic who responded to the accident had to be airlifted to St George Hospital after slipping down a ravine and suffering serious leg and ankle injuries.