Police commissioner Mike Bush is applauding the bravery of Christchurch officers on the ground during a horror incident, following which four people are in custody.
Gunmen opened fire at two mosques in Christchurch. There were reports of between nine and 27 people killed in the incident.
Speaking to media this evening, Bush said police had taken four people - three men and one woman - into custody.
"This is absolutely tragic," Bush said of the incident.
"So many people are affected."
Police could not confirm the identities of any victims, as the locations of the shootings remained in lockdown.
Police were setting up a facility dedicated to providing information around the shootings, and the security situation around the city.
A number of IEDs attached to vehicles that were stopped had been made safe by the NZ Defence Force.
He said he would not assume there aren't other attackers - but there was also no information to suggest there was.
"I want to assure the public we are doing everything we can to make sure there is no more harm to their communities," Bush said.
"It doesn't get any more serious in this country".
"Of course our staff will have immediate access to the equipment they need to keep themselves safe."
A number of schools had been in lockdown and police worked with schools to make sure everyone got home safely.
Police also had the mosques locked down.
The commissioner confirmed police were aware footage of the shooting was circulating online.
He called the footage "very disturbing" and said police were working to remove it.
A body has been seen lying near Al Noor Mosque in central Christchurch and a second gunman has been seen near Linwood Masjid mosque. One of the gunmen broadcast live as he shot victims.
One of the gunmen is believed to be an Australian who has written a manifesto declaring his intentions.
In it, he says "it is a terrorist attack."
The multiple fatalities were at two locations - a mosque at Deans Ave and one at Linwood Ave.
There are reports of a third active shooting unfolding outside Christchurch Hospital.
A Christchurch Star reporter saw a body lying close at Palazzo Lane near Al Noor Mosque.
The body has been covered with clothing.