Police have confirmed three people are in custody and multiple car bombs have been disarmed after the shooting at two mosques in Christchurch today.

Watch the first police media conference here:

Watch the second police media conference here:

There have been two shooting incidents - at the Masjid Al Noor Mosque next to Hagley Park, and at the Linwood Masjid Mosque in the suburb of Linwood.

Police Commissioner Mike Bush confirmed 49 people have been killed.

While four people were originally arrested over the attacks, one is no longer in custody.

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At the 5pm press conference, Mr Bush told media there were a number of car bombs that had also been handled.

"There were a number of IEDs (improvised explosive devices) attached to vehicles that we also stopped. They've been made safe by Defence Force but that does go to the seriousness of the sitaution," he said.

He said the four suspects had been captured by local police staff, and police had locked down the mosques where the attacks took place.

"There's been some absolute acts of bravery ... but let's not presume that the danger is gone.

"We are not aware of other people but we can not assume there are not others at large.

"We're not assuming that this is contained to Christchurch, we have no information to suggest that it is ... at this point in time we can't make assumptions.

"This is requiring every police and emergency resource that we have available."

Photo: RNZ / Rebekah Parsons-King

Police were flying in more staff from other regions, and were setting up a facility so that people can phone in and check on their loved ones, he said.

"We don't have the identity of the people who have died as yet."

He said there was social media footage of the attack which they were trying to suppress.

"It's very distuburing, it shouldn't be in the public domain and we are doing everything we can to remove it.

Asked if it was a terrorist attack, he said police were still looking into the circumstances around that.

All Christchurch schools, Christchurch Hospital and Christchurch City Council buildings have been placed into lockdown. Multiple roads in the city, including Blenhein Rd, Moorhouse Ave and Brougham St, have been closed.

Mosques across the country have been told to shut their doors, and

Prime Minister Jacinda Ardern said it was clear this was "one of New Zealand's darkest days".