Bravery lauded after 'heroic' arrest

Police Commissioner Mike Bush has commended his "courageous" officers who arrested the alleged Christchurch gunman 21 minutes after they were alerted while he was en route to another attack.

Bush has provided updated information, saying it took 5 minutes and 39 seconds for police to be armed and on the scene ready to respond to the attack. In 10 minutes the armed offenders squad was on the scene.

"In 21 minutes the person now in custody was arrested, from when we were first notified to when ... he was arrested, away from further harm for the public," Bush said.

"We strongly believe we stopped him on the way to [a] further attack. Lives were saved."

Police Minister Stuart Nash said the commissioner could not believe how fast the alleged shooter was arrested.

"We are talking about a big city ... to have the guy arrested either within 20 minutes or 35 minutes, I think is extraordinary," Nash said.

Nash also revealed more details around the man's arrest.

"These two guys pull this guy out but at the same time he was yelling, 'I've got a bomb' and shooting at the same time, so we overuse the word hero, but not in this case."

When asked if the officers would be receiving bravery awards, Nash said he could not "pre-empt anything" but there "aren't too many more acts of bravery higher than that".

The timeline of events for Friday's attacks which killed 50 people and wounded another 50 was about 40 minutes.

The accused gunman was arrested by two officers on Brougham St, following the shootings at both the Deans Ave and Linwood mosques.

The two officers, who had just come from a training session, rammed his car off the road in order to stop him.

Bush said this was "absolutely an international investigation".

It involved New Zealand police, the FBI, Australian police, and Five Eyes partners.

Bush confirmed there was one attacker.

"A focus [of the investigation] is to figure out if anyone else was supporting him in any way."

At the accused's next court appearance, at the High Court on April 5, there would "undoubtedly be more charges", Bush said.

"We are working towards, as you can imagine, a considerable number of the most serious charges."

Police had now formally identified 21 victims and their bodies would be released to their families.

While for police the number one priority was victims and families, on behalf of the Chief Coroner it was to ensure absolute accuracy in the identification process.

The other responsibility was prosecution. "We must prove the cause of death to the satisfaction of coroner and judge. You cannot convict for murder without that cause of death."