Christchurch terror attack: Jacinda Ardern demands answers over security failures

The Prime Minister spent Saturday in Christchurch leading a cross-party delegation of MPs to hear the concerns of the communities targeted in Friday's attack.

And she's demanding an urgent review into why the attacks weren't prevented and why our security services didn't see the signs.

The more we learn about Brenton Tarrant the harder it is to understand why he wasn't known to our security services.

"Again, I reiterate that this individual was not on the radar, of either Australian intelligence agencies or New Zealand intelligence agencies," Ms Ardern says.

Two days before the attack he posted images of weapons painted with extremist references - including 'Here's your migration compact' - referring to the United Nations pact New Zealand signed up to which was targeted by far-right groups.

"I have asked our agencies this morning to work swiftly on assessing whether there was any activity on social media or otherwise that should have triggered a response. That work is already underway. Today as the country grieves we are seeking answers," Ms Ardern says.

There should have been red flags. He got his gun licence in November 2017 and started buying firearms the next month.

In 2018 he travelled to Pakistan - a no-go travel zone for New Zealanders and Australians before returning to New Zealand to plan his attack.

The Prime Minister has demanded an urgent explanation from her top officials.

"I have instructed ODESC to report to cabinet on Monday on this sequence of events with a view to strengthening our systems on a range of fronts including but not limited to firearms, border controls, enhanced information sharing with Australia and any practical reinforcement of watch list processes," she says.

An overhaul is coming - but it cannot undo the horrors of yesterday.