The victims fell in two locations: the first in a mosque on Dynes Street, and the second in another mosque on Linewood Street.
There are four people in detention, three men and one woman.
Police successfully dismantled explosive devices found in the defendants' cars.
Residents of Christchurch's center were invited to commit to their homes and to report suspicious movements to anyone.
New Zealand media reported the deaths of more than 40 people, and the injury of dozens of cases, some of them serious. Police previously announced the arrest of one person in custody, likely to be involved in the attack.
According to media reports, one of the perpetrators, a 28-year-old Australian, has an extremist racist ideology and has a video of himself shooting at worshipers in the mosque.
According to the New Zealand Herald, the accused of the attack published a 37-page "statement" in which he reported his intentions.