Sydney nun Sister Philomene Tiernan is among the 28 Australian victims of the Malaysia Airlines disaster.

To the world, she is one of 298 victims of the Malaysia Airlines disaster, but to students of an exclusive Sydney school, she was like a grandmother.

Sydney nun Sister Philomene Tiernan was on board flight MH17 when a suspected surface-to-air missile struck it, killing everyone on board.

She was among 28 Australians on the plane.

Sister Philomene worked for more than 30 years as a teacher and director of boarding at Catholic school Kincoppal-Rose Bay, in Sydney’s east.

A year 12 boarding student, outside the school, spoke of her shock and sadness.

“The impact of this is just unbelievable in the whole community,” the student, who did not want to be named, told AAP.

“It comes as a shock to us all.”

The nun had been enjoying a sabbatical in France.

“I feel like since we are all away from our parents she seemed like a grandma that everyone just loved,” a year 10 student said.

The school has educated some famous faces, including Gai Waterhouse, Ita Buttrose, Lucy Turnbull and Princess Michael of Kent.

“Many women incl my wife Lucy & daughter Daisy were inspired by the love of Sr Phil Tiernan RSCJ. God bless her & all who died in MH17,” Communications Minister Malcolm Turnbull tweeted.

Kincoppal-Rose Bay principal Hilary Johnston-Croke earlier described Sister Philomene as a friend and mentor who had brought love to the school community.

“We are devastated by the loss of such a wonderfully kind, wise and compassionate woman who was greatly loved by us all,” she said in a letter to parents.

“She contributed greatly to our community and she touched the lives of all at KRB in such a positive and meaningful way.”

Mrs Johnston-Croke said her main focus was on helping students deal with the loss.

“These sort of events are just huge shocks to young people,” she said outside the school.

Monsignor Tony Doherty, the parish priest at Rose Bay’s St Mary Magdalene Catholic Church, has known Sister Philomene for about 30 years.

“She’s an incredibly gentle personality – one of those blithe gentle spirits that you never just touch without coming back a bit enriched,” he told ABC radio.

“Her contact with the young women at Kincoppal was powerful.”

Monsignor Doherty will lead a special prayer service for her on Saturday at 9am.

“We’ll be having a mass to focus our grief and loss of such an extraordinary woman,” he said.

Sister Philomene had an award named after her for boarding students.

The school is offering counselling to students.

Former deputy principal Michael Clancy and his wife Carol are believed to have perished on MH17.

Albion Park Public School, south of Wollongong, released the news in a letter to parents on the school’s website on Friday evening.

“Sadly, I must inform you that Mr Michael Clancy and his wife, Carol are believed to have been on board that flight,” said principal Glenn Daniels.

“Mr Clancy retired at the end of last year after serving this community as a highly respected teacher and Deputy Principal for the past 22 years.”

“As Mr Clancy is known to so many of us in the community, we have chosen to provide you with this sad news.”

Mr Daniels said counselling and support would be made available for students next week.

Premier Mike Baird said there were now “at least” three confirmed NSW victims.

“On behalf of the government and all of the people of NSW, I express my sadness and my condolences to the families of those involved,” he said in a statement.