Yesterday evening, the death toll for the Easter Sunday bombings was at least 290, with an estimated 500 people wounded.
The attacks targeted churches and hotels in the cities of Colombo, Negombo and Batticaloa.
Otago Sri Lankan Students' Association president Malshi Premaratne said members were "devastated and heartbroken''.
The group expected vigils and fundraisers would be organised.
However, it requested support from the public due to the shock its members were feeling.
Christchurch and Colombo were Ms Premaratne's two homes, so it felt surreal both cities were hit by terror attacks in just over a month, she said.
While it was easy to feel hopeless, the best thing to do was keep a clear head and put energy into the things under your control, she said.
St Anthony's Church, which was the target of one of the explosions, was a welcoming and holy place that her parents took her to several times when she was sick as a baby.
"I am so passionate about the unity between religions which this church stands for.''
Ms Premaratne moved from Sri Lanka to New Zealand when she was 3, but because extended family lived there, it always felt like home.
"We're all in a fair bit of shock. Sri Lanka has been a pretty peaceful place for the last 10 years since the end of the civil war.''
Association secretary Rahul Rahubadde said if New Zealanders wanted to help, small actions like checking on Sri Lankan friends was "more than enough''.
"Your support is invaluable, and it's what all Sri Lankans need during this difficult time.''
Queenstown woman Dinesha Amarasinghe said she called all her relatives in Colombo - including her mother, brothers and sisters - as soon as she heard the news on Sunday evening.
"My family and everyone is safe, but I know a lady and her daughter who passed away.''
One of the bomb blasts was only about 30 minutes' drive from her old home.
Her family had told her a police curfew was in place, and they were staying inside their homes.
An emotional Mrs Amarasinghe said it had been distressing to watch the news unfolding on television, and see the number of fatalities keep rising.
Sri Lanka had been peaceful since the war ended, she said.
"I didn't think these things would happen again.''
She and husband Sam emigrated to New Zealand with their children in 2010.
Dunedin Tamil Society president Lux Selvanesan said for him and other Sri Lankans in the group, the attacks were still raw.
"We would like to give our condolences and support to all those affected, especially at such a spiritual time for them.''
Mr Selvanesan lived in Negombo as a student and was yesterday contacting friends and their families to ensure they were safe.
He described it as a "beautiful place'' with beaches which attracted many tourists.
Society members would help in any way they could.
