Tracy O'Brien pictured at Cullinane College in 2010, when it was announced he was moving south.
Whanganui's Cullinane College community is in shock after its founding principal, Tracy O'Brien, died following a sudden medical event.
O'Brien, who was 54, died overnight on Monday, March 18.
He was principal at Cullinane College between 2003 and 2010. The Catholic secondary school was created by the amalgamation of Sacred Heart and St Augustine's colleges and O'Brien was its first principal.
"This has come as a great shock to past and present staff and students and has sent a sadness through our community," Cullinane College posted on its Facebook page.
"Please keep Tracy, his wife Vicky, and children Nathan and Caitlin in your thoughts and especially your prayers."
"I remember him as principal when I attended Cullinane College, taught me how to tie my school tie when I started," said Carolanne Shaye.
Paddy Monaghan added: "Very sad news after a week that has seemed filled with it."
"Tracey, your hard work and leadership throughout the formative years of our kura really has had a lasting impact on both the students and teachers, which I have observed from both sides. As the school song goes 'let us stand upon their legacy' - rest easy sir."
The school held a memorial liturgy for O'Brien on Tuesday and its flag is flying at half-mast.
"Words about how important he was in creating our college and the impact he had on the values that we uphold to this day, were shared. Our college stood for a minute's silence as we remembered our foundation principal."
Past students and their families paid tribute via Facebook to the man fondly known as "Mr O'Breezy", many students remembering him as their favourite principal.
At the time of his death, O'Brien had been principal at Dunedin's Kavanagh College for nine years and in October last year announced he would be resigning at the end of term 2 this year, and was looking forward to retirement.
After almost 20 years as a principal in New Zealand schools, he said he felt it was time for new horizons.
Before being appointed principal at Cullinane College, O'Brien was acting principal for a year at Hato Petera College in Auckland, and a history and economics teacher for the previous 14 years.
Principals across the country said they were shocked at the news of his death, and paid tribute to him, describing him as a wise, relaxed, lovable, affable, kind, empathetic person with a great sense of humour and a tremendous passion for education.
A memorial Mass will be held at Kavanagh College today.
Deputy principal Steve Read said it had been humbling to see how staff and pupils had supported each other after the death.
"We have been grateful for the many messages of support from parents and other schools.