Christchurch terror attack: Sam Neill's 'helpless anger' after deaths

Actor Sam Neill says he's struggling to understand the horrific Christchurch terrorist attacks which have left 49 people dead so far.

The actor spoke to Newshub outside the Ponsonby Mosque on Saturday, surrounded by the flowers and messages left by the grieving public.

"I cannot begin to describe the helpless anger I feel today and the heartbreak too this sends," he said.

"It's unthinkable and I'm only beginning to grasp the whole enormity of it now."

Vigils are being held across New Zealand today in memory of the victims. One is taking place at Aotea Square in Auckland, and crowds continue to gather near the mosque by Christchurch's Hagley Park.

"That a hate crime of this magnitude should be possible at all... my heart goes out to all those people in Christchurch who are affected by this," Neill told Newshub.

"That should happen to a beloved section of our community is beyond belief and I can't begin to express how I feel. I am so sorry."