Children are among the 48 people being treated for gunshot wounds.
Ardern said police would be posted at all mosques while they are open. No images have emerged from there.
Facebook said it had deleted the gunman's accounts "shortly after the livestream commenced" after being alerted by police.
The AP also reported that Tarrant, who has donated to a number of white nationalist groups but has no other direct affiliation with them, allegedly was given personal approval by Breivik to commit the mosque attacks in Christchurch, though this has yet to be verified.
Ardern's office said the suspect sent the "manifesto" by email to a generic address for the prime minister, the opposition leader, the speaker of the parliament and around 70 media outlets just minutes before the attack.
Friday's attack, which Ardern labeled as terrorism, was the worst ever peacetime mass killing in New Zealand and the country had raised its security threat level to the highest.
Ardern said she had asked authorities to look into whether there was any activity on social media or elsewhere ahead of the attack that should have triggered a response.
"I got told by my best friend's father. that he leaped on somebody else to save their life", he told Stuff.co.nz.
New Zealand law enforcement is working with Australian intelligence and police in the "wide-reaching" investigation, the commissioner said.
As Khan tried to comfort one of the victims of Friday's massacre inside the Linwood Islamic Center, white supremacist gunman Brenton Tarrant took aim once more, shooting the dying worshiper in the head, he told CNN.
"We think also of our Cook Islands community in Christchurch and in New Zealand, with so many of our people who have made their homes there". One victim died in hospital.
"Our prayers are with the families of the deceased, the injured and all others impacted by this tragedy".
"Hi guys how are you".
A message card is placed at a collection of flowers left at the Botanical Gardens in Christchurch, New Zealand, Saturday, March 16, 2019.
Ardern, however, stopped short of suggesting New Zealand could implement a similar policy in the wake of the attacks in Christchurch.
A few hundred demonstrators have protested the New Zealand mosque shootings outside Istanbul's Hagia Sophia - a Byzantine-era cathedral that was turned into a mosque and now serves as a museum.
TESSA BURROWS via Getty ImagesResidents pay respect by placing flowers for the victims of the mosques attacks in Christchurch on Saturday.
Most of the victims of the attacks were immigrants from Pakistan, India, Malaysia, Indonesia, Turkey, Somalia and Afghanistan.
The New Zealand premier was showered with enormous praises internationally for the gesture, which made it clear that New Zealand stood by the Muslim community that was the centre of Friday's horrifying terror attacks rooted in racial as well as religious hatred.
Former Eagles WR Golden Tate stays in the NFC East
Tate acknowledged the signing on Twitter, tweeting an image of the "I love New York" logo and making it his new profile picture. And according to Ian Rapoport of the NFL Network, the Pats are actually showing interest in the veteran slot receiver.