The bodies of the victims had not yet been released to families because investigations were ongoing, but police were working as quickly as they could to do that, Bush said at a media conference in Wellington.
Ardern was joined by Australian Prime Minister Scott Morrison in expressing doubts that current rules go far enough.
"What you should judge our relationship by is what has happened after the event, and the relationship is strong; we have heard from so many Australians who want to help, who see us as their brothers and sisters", Dame Annette said.
Brenton Harrison Tarrant, 28, has been charged with murder in relation to the massacre on Friday, in which 49 people were killed and 42 injured. But the 87-page document, also posted on social media just before the shooting began, was filled with anti-immigrant, anti-Muslim screeds.
Within two minutes of its receipt, Ms Ardern said the email - which she confirmed she had read parts of - was forwarded by her office to parliamentary security.
One additional victim was found at the Dean Ave Mosque.
Forty-one people were killed at the Al Noor mosque.
Twelve operating theatres worked through the night on the more than 40 people wounded, said hospital authorities.
Police have not released the names of those killed in the attack, but charging documents listed one of the victims as Salwa Mirwan Mohamad. About two dozen men received instructions on their duties Sunday morning, which included Muslim burial customs. "Prince Philip and I send our condolences to the families and friends of those who have lost their lives".
"In the midst of this bad atrocity this is the hope we can cling to, peace-loving and free people all around the world", he said.
"In these times of mourning and recollection, our common values, that of a Polynesian world that lives in fraternity and respect for everyone, will help us overcome this awful ordeal". Her father Waseem, 33, is said to be in a stable condition.
"The family understands that it's a crime scene".
"A category-A firearm holder can purchase the firearms without the magazines or the things that will enable them to be in the state that they were", Bush said. - AP Mourners pay their respects at a makeshift memorial near the Masjid Al Noor mosque in Christchurch, New Zealand, Saturday, March 16, 2019. "50 hearts for 50 lives".
The gunman livestreamed 17 minutes of the rampage at the Al Noor mosque, where he sprayed worshippers with bullets.
The second attack took place at the Linwood mosque about 5 kilometers (3 miles) away.
Ardern said the suspect was a licensed gun owner who bought the five guns used in the crimes legally.
Two other armed suspects were taken into custody Friday while police tried to determine what role, if any, they played in the cold-blooded attack that stunned New Zealand, a country so peaceful that police officers rarely carry guns.