Police are responding to an 'active shooter' situation at a mosque here, according to local media.
"A serious and evolving situation is occurring in Christchurch with an active shooter," Al Jazeera quoted Police Commissioner Mike Bush as saying.
Local media reports suggest that a gunman entered a mosque here on Friday and started shooting with an automatic weapon.
"A gunman - dressed in black with a helmet carrying a machine gun - came into the back of the mosque and started firing into the people praying there," Al Jazeera quoted local media as saying.
People as young as 16 years are reported to have been inside the mosque at the time of firing.
Several casualties are feared, as authorities are yet to confirm the exact figure of deceased or wounded.
Further information is awaited.