Brenton Tarrant also planned to burn down the mosques, wanting to "inflict as many fatalities as possible".
The Australian has pleaded guilty to 51 counts of murder, 40 attempted murders and one charge of terrorism.
Tarrant, 29, faces life in prison, possibly without parole - a sentence never before imposed in New Zealand.
The attacks, parts of which the gunman streamed live online, sent shockwaves around the world and prompted New Zealand to make swift changes to its gun laws.
