Deputy principal Ali McHugh described the former student as a "quiet and friendly boy" who was well-liked by others.
"He always had a smile on his face. He was thoughtful to other students and was an all-around lovely boy," McHugh said.
"Our thoughts and love are with the family at this time. They should be very, very proud of their young man because he was a lovely boy at school, and he had great friendships with his peers."
It is understood he left school in 2018.
McHugh said the former student played football in his junior years at the school.
Support would be in place for affected students when school returned in Term 4, she said.
A police spokeswoman said emergency services were called to a single-vehicle crash on Te Ngae Rd about 11pm Saturday. Four people were involved in the crash.
The police spokeswoman confirmed one person was taken to Waikato Hospital in a critical condition, where they have since died.
A St John spokeswoman said two ambulances responded.
St John treated one patient in a critical condition and two patients in moderate conditions and took them to Rotorua Hospital. St John also treated one patient in a minor condition at the scene.