The death toll from the Christchurch shootings has risen to 50 after a victim, previously not accounted for by police, was discovered at one of the mosques.

Key points: Thirty-six people remain in Christchurch Hospital, two of whom are in a critical condition

Thirty-six people remain in Christchurch Hospital, two of whom are in a critical condition A so-called manifesto written by the gunman was not sent to police before the attack

A so-called manifesto written by the gunman was not sent to police before the attack Members of the public have been asked not to circulate a list of victims' names

A gunman with a semi-automatic weapon massacred worshippers gathered for Friday prayers in two locations: a mosque at Deans Avenue in central Christchurch and another mosque in the nearby suburb of Linwood.

New Zealand Police Commissioner Mike Bush said a further examination of the crime scene allowed them to find another victim.

"As of last night, we were able to take all of the victims from both of those scenes and in doing so we have located a victim," he said.

A further 50 people were injured in the attack, Commissioner Bush said, and 36 remain in the Christchurch Hospital, twelve of whom are in the Intensive Care Unit in a critical condition.

Four people were arrested, but only 28-year-old Australian man Brenton Tarrant has been charged with murder.

Commissioner Bush said two people, a man and a woman, were arrested at a police cordon during the operation on Friday.

He said they had gone to "assist children in the area to get them safely, but did decide to arm themselves".

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 2 minutes 2 m NZ Police Commissioner Mike Bush confirms the death toll has risen to 50.

The woman was released without charge, while the man was charged with firearms offences, he said.

An 18-year-old man was also arrested during the course of the operation and will appear in court on Monday.

However, that arrest was "tangential to this matter and we do not believe that he was involved in this attack either", Commissioner Bush said.

Gunman emailed manifesto to PM's office before attack

Commissioner Bush said a so-called manifesto written by the gunman was not received "at a time prior to the attack".

The email outlining Mr Tarrant's reasons for his actions was sent to a general email address for Prime Minister Jacinda Ardern's office which is handled by her staff.

It was also sent to the office of the Opposition Leader, the Speaker, and the parliamentary tour desk, along with a number of media outlets.

The Prime Minister's staff handled the email according to procedure and referred the message to parliamentary security. It was then handed on to police.

"It was forwarded to us sometime during the day. Obviously by some of the recipients, but not at a time prior to the attack," Commissioner Bush said.

"By the time we were advised of that email, the attack had taken place."

Commissioner Bush praised police for their response to the attack, with the accused gunman taken into custody within 36 minutes of the first call to emergency services.

He said the officers "acted with absolute courage".

Members of the public have been mourning in Christchurch. ( ABC News: Brendan Esposito )

"I'm so proud of what they've done," he said.

"They have prevented further deaths and again, risked their own lives to do so."

List of victims' names compiled, formal identification ongoing

Commissioner Bush said a list of victims' names had been compiled to "give some certainty to victims' families", but added the process of formally identifying bodies was ongoing.

He asked members of the public to avoid circulating lists of people's names.

"That list was compiled as a result of work done with victims and with senior religious leaders and was done to give some certainty to victims' families," he said.

"This is not a formal list. And we will be unable to share exact details of victims until they have been formally identified."

Immigration New Zealand has arranged priority processing for the families of those killed or injured in the shootings to obtain visas into the country, and Commissioner Bush said authorities were working "as quickly and sensitively as possible".

There has been an outpouring of grief for the victims of the shootings. ( ABC News: Brendan Esposito )

A number of patients are expected to be discharged from the Christchurch Hospital's Intensive Care Unit to surgical wards on Sunday, with plans to prioritise, "those patients from the mosque attack for surgery over the coming days".

"Presently, there are seven acute theatres operating," said Christchurch Hospital's chief of surgery Greg Robertson.

"Normally we would be running three on a day like today.

"We do see gunshot wounds. We do see all these type of injuries, but, you know, 40 or 50 people in a day is more than what we should see."