Support at Ysgol Bro Morgannwg after A470 Brecon death crash
Support is being given to pupils at a Vale of Glamorgan school and a Cardiff college after three teenagers were involved in a fatal crash in Powys.
Alesha O'Connor, her boyfriend Rhodri Miller and Corey Price, all 17 and from Barry, died in the collision near Storey Arms, Brecon, late on Friday.
Margaret Elizabeth Challis, 66, from Merthyr Tydfil, was also killed.
Three others are in hospital - one is in a critical but stable condition. The others are described as stable.
Seven teenage boys were arrested on suspicion of dangerous driving.
It is believed they had been travelling in convoy at the time. All have now been released on bail.
Head teacher Dylan Jones, of Ysgol Bro Morgannwg where Corey and Rhodri had both been pupils, said the school came together on Monday to remember them and celebrate their lives.
He said counselling was being offered to students, while a special assembly had been held for sixth formers and books of condolence had been opened.
He said Rhodri had been a scientist and "had a good future in front of him with with the sciences".
He added: "Corey had been a talented sportsman and had been with Cardiff City for some time".
"We remember them as smiling, mischievous young people doing really well in their own fields but also part of a strong group of friends," Mr Jones said.
"And that friendship is to be seen here today."
The teenagers' friend Matthew Howe said he had been taking friends and fellow pupils to hospital to see those who were injured.
"We just need to group together and come together as a group of friends and see if we can make everyone feel a little bit better," he added.
St David's College in Penylan, Cardiff, which Alesha attended, said it was giving support to "shocked and very upset" pupils and staff, while opportunities for prayers and reflection would be offered.
Paying tribute to her, it said: "Alesha was a wonderful individual who will be deeply missed.
"Alesha joined our college community in September 2014 from St Richard Gwyn High School and in a short time she made an immensely positive impression on us all.
"We were privileged to have Alesha with us, she was a talented student and delightful personality."
Mark Leighfield, principal of the sixth form college, said students had gathered in the college chapel on Monday morning to remember Alesha and a mass in her memory was planned for later this week.
The college students' union had also set up a memorial box to allow fellow students to leave their memories of Alesha, and it will be delivered to her family.
BBC Wales reporter Stephen Fairclough, at Ysgol Bro Morgannwg
Many of the children arrived for school on Monday morning looking visibly upset and were hugging in groups close to the school's main gates.
After the morning's special assembly, some pupils left the school. Others remained to view the many floral tributes which had been brought.
Alongside flowers were football shirts and a Cardiff City football flag as both boys were supporters of the club.
At the gate, a home-made sign was placed saying: "Cysgwch mewn hedd", which means rest in peace in Welsh.
Underneath was a line in Welsh quoting Buddha: "The problem is you think you've got time."
Police community support officers were also outside the school.
On Sunday, Rhodri's parents described him as a bright, talented 17-year-old, while Alesha's family paid tribute to a "beautiful, intelligent and artistic" girl.
Corey's parents said they were "devastated" by the death of "their wonderful gentle and caring son, brother, uncle and grandson".
He had been a member of the Cardiff City Academy since the age of nine. A one-minute applause in tribute to him was held in the 17th minute of the Bluebirds' match against Charlton on Saturday.
Rhodri was a former junior player with Dinas Powys FC and his father still coaches at the club.
Friends also released lanterns at the Knap in Barry over the weekend in memory of those who died.
The collision, involving a green Volkswagen Golf and a black Volkswagen Golf estate, happened on the A470 at about 22:15 GMT on Friday.