KEY POINTS:

Reports gunman opened fire inside mosque in Christchurch's Hagley Park

Man describes running for his life as at least two gunmen opened fire

Armed police also at second mosque in suburb of Linwood

Police tell everyone in centre city to stay indoors

Police are reportedly at Christchurch Hospital searching for explosives

Forty-nine people have been killed and 48 people hurt after gunmen stormed two Christchurch mosques in the worst terror attack on New Zealand soil.

Police Commissioner Mike Bush said the shootings were "abhorrent". At the Deans Ave mosque 41 people were killed, while seven had died at the Linwood mosque. A 49th person had died in hospital.

One man in his late 20s had been charged with murder so far, Bush said.

Anxious family and friends are pacing outside Christchurch Hospital, waiting for news of injured loved ones.

Wailing and crying can be heard at intervals, as people learn their friends will not be coming home.

"We just got some very bad news," said Mahdi Zougub, as his friends hugged nearby.

"We think our friend... we think he's gone. There's a lot of emotion."

Zougub, 22, said he was on his way to the Deans Ave mosque when a friend called and told him about the shooting. He wasn't allowed inside.

"I could see dead bodies. Now we are just waiting to hear the story with our missing ones. We just want to go in and find them."

Some of the shooting victims have been released and allowed to go home.

One, with a wound on his hand and another on his leg, said his phone and wallet were in the mosque and he had no way to call a taxi.

I can't believe it," he kept saying.

"My children... I'm just relieved I didn't take them to prayer today."

A social worker eventually helped the man get a cab - although there are long lines as many of the taxi drivers are from the affected community.

Armed police remain stationed outside the hospital.

Speaking about the victims Bush said: "Our love and thoughts go out to them and all of their family, all of their friends and all of their loved ones.

"We have staff around the country making sure everyone is safe, including armed offenders at all mosques. Police staff have gone above and beyond to protect people today."

Bush said police recovered a lot of firearms from both the Linwood Avenue and Deans Ave shooting scenes.

None of the four people arrested had been on any terrorism watch, including in Australia, the Police Commissioner said.

Police were not "actively" looking for any of the potential attackers now.

Earlier Prime Minister Jacinda Ardern said 10 were killed at Linwood and 30 at the Deans Ave mosque near Hagley Park.

She said a further 20 people were seriously injured, while Christchurch Hospital has just confirmed 48 people suffered gunshot wounds. Four people were arrested - three men and one woman.

Ardern said it was an "unprecedented" situation and described it as a terrorist attack.

"It is clear that this can only be described as a terrorist attack. From what we know, it does appear to have been well planned. Two explosive devices attached to suspects' vehicles have been found and they have been disarmed."

A police officer escorts a man away from a mosque in central Christchurch. Photo: AP

Those in custody had not been on any terrorism watch list: "It's not a matter of someone having slipped under the radar," Ardern said.

"There are currently four individuals who have been apprehended but three are connected to this attack and are currently in custody, one of which has publicly stated that they were Australian born.

"These are people who I would describe as having extremist views that have absolutely no place in New Zealand and in fact have no place in the world.

"While we do not have any reason to believe at this stage that there are other suspects, we are not assuming that at this stage.

Ardern said it was obvious the attacks had been planned for some time. Three people were arrested in relation to the attacks, while one other was arrested separately.

Ardern said she could not give any more detail about the alleged offenders.

An Australian-born suspect had been in New Zealand "a relatively short time".

She said she was asking questions about them, including access to firearms, of her officials.

The National Security Threat Level had been lifted from low to high.

The Defence Force was transporting more police to Christchurch.

Ardern said New Zealand was a place of safety where they raise their families.

"Those values will not and cannot be shaken," she said.

"This is a place where people should feel secure."

David Meates, chief executive of Canterbury District Health Board, said Christchurch Hospital and other health clinics were treating 48 patients for gunshot wounds.

The people shot range from young children to adults and injuries ranged from critical to minor.

Twelve operating theatres were currently in use and many people would need multiple surgeries.

There was sufficient capacity and staff at Christchurch Hospital, Meates said.

Witnesses have described the horror as it unfolded, some of which was filmed by an attacker, including a man who told Christchurch Star, he crawled to safety amid the carnage of the shooting.

"I saw people drop dead in front of me. I was crawling to get away."

"It was hitting the walls," he said.

A Christchurch Star reporter saw a dead body lying near Al Noor Mosque.

A man reacts as he speaks on a mobile phone outside a mosque in central Christchurch. Photo: AP

The multiple fatalities were at two locations - a mosque at Deans Ave and one at Linwood Ave.

There were also reports of a third active shooting unfolding outside Christchurch Hospital.

Australian Prime Minister Scott Morrison has confirmed an Australian-born citizen has been taken into New Zealand police custody over the Christchurch mosque shootings.

The Police Commissioner Mike Bush said "there have been some absolute acts of bravery" in the arrests of the four attackers.

A number of IEDs that were attached to vehicles in Christchurch have been defused.

Bush said there were multiple casualties - a "significant" amount.

"This is absolutely tragic. So many people are affected.

"We don't have the identities of those who have died yet because those places are in lockdown."

He said he would not assume there aren't other attackers.

He confirmed police were dealing with two shootings at two mosques in Christchurch, one at Deans Ave and one at Linwood Ave.

Those locations remain locked down.

"We can confirm there have been a number of fatalities.

"So far, four people, three men and a woman, have been taken into custody after being apprehended by Police.

"We are speaking with those people.

Bush said he was aware that footage of the Al Noor Mosque shooting was on social media and police were doing everything they could to get it removed.

"It shouldn't be in the public domain."

"We are currently dealing with an unprecedented situation in New Zealand. It's very grave, it's very serious."

When asked if it was true that a person had been arrested wearing wired explosives, Bush said that person had been "made safe."

"We're still working through that but we believe there was a claim but that person has been made safe."

Police are still treating the incident as ongoing and Christchurch residents are strongly urged to stay indoors and keep safe, and monitor the Police website and social media for further information.

"We continue to utilise every possible resource to resolve the situation.

"Police work with a number of agencies in preparation for events of this nature and we have plans and procedures in place which we are following.

"We are receiving assistance from NZDF, Ambulance, Fire and Emergency New Zealand, and wider Government.

"At this stage we will not be discussing the offenders’ possible motivations or the causes of this incident.

"We have asked all mosques nationally to shut their doors, and advise that people refrain from visiting these premises until further notice.

"The lock down of schools through Christchurch has been lifted."

Addressing a media conference in New Plymouth earlier today, Ms Ardern described the events in Christchurch as this one of New Zealand's darkest days.

Ardern described the event as "extreme and unprecedented violence".

Ardern looked to be struggling to keep her emotions in check as she spoke.

Police hold a suspect down on the ground. Photo: NZME

Police issued an update just before 5pm saying that due to the ongoing situation schools across the city remained in lock down, but by 5.50pm it had been lifted.

"We would like to reassure members of the public that there is a large Police presence in the city and the safety of the community is our priority."

The gunman who attacked the mosque appears to have posted the shocking killing spree on Facebook.

Nineteen seconds of footage was posted on Christchurch Police Check Points page. The page is not connected with the police.

The appalling footage which was filmed with a GoPro shows people lying on the floor as the gunman shoots them with an automatic weapon.

The video was taken off the site soon after it appeared.

Ambulance staff take a man from outside a mosque in central Christchurch. Photo: AP

One of the gunmen is believed to be an Australian who has written a 37-page manifesto declaring his intentions.

In it, he says "it is a terrorist attack."

"I saw people drop dead in front of me."

A man, who would only be known as Nour, who crawled to safety amid the carnage of the shooting has told of what happened.

Nour in the front row of prayers when the gunman came in.

"First he shot people outside. Then he came in the front," he said.

He heard the gun being reloaded about three times.

Armed police patrol outside a mosque in central Christchurch. Photo: AP

The gunman began shooting in all directions.

"I saw people drop dead in front of me. I was crawling to get away."

"It was hitting the walls," he said.

Nour crawled across the floor of the mosque to a window that had been broken by others as they fled and jumped trough it.

He jumped over a neighbouring wall. He ran around the block and he could still hear shooting.

A person who had been told by a man in the mosque said: "A gunman came in in with an automatic gun and opened fire, spraying it from side to side."

Police at the shooting in Christchurch. Photo: Supplied via NZME.

There were also reports of a third active shooting unfolding outside Christchurch Hospital, and the Guardian reported police as saying there was a bomb on Strickland Street in Christchurch.

"The bomb is located inside a beige Subaru that has crashed on Strickland Street, about 3km from the Al Noor Mosque where the shooting took place," the Guardian reported.

"You're not safe here, there's a bomb in that car," a senior police officer told reporter Eleanor Ainge Roy earlier today.

Tears outside mosque

Meanwhile, people gathered outside the police cordon at the scene of the shooting appear connected to the mosque.

Many of them were crying. People were slowly starting to emerge from within the cordon, very distressed.

Several witnesses were the escorted away from the scene and the cordon by police officers.

One person told a Christchurch Star reporter that police had told them there aunt had been shot dead in the mosque and another person said police had told them their father had been shot dead.

A gunman was earlier reported as being in the is in the Botanic Gardens, but a woman in the Botanic Garden's Ilex cafe said they had been told the gunman was near or at Christchurch Hospital - but this remains unconfirmed.

People in the cafe had to move to the back of the building, the doors had been chain locked and no-one could sit near the windows.

Ambulances outside Christchurch Hospital as a major situation unfolds. Photo: Christchurch Star

There had been a conference at the cafe.

"No one has come in panicked," she said.

Police earlier surrounded the Botanic Gardens.

Ambulance staff take a man from outside a mosque in central Christchurch. Photo: AP

Mohamed Warsame said his brother who is 26 and his mother were in the mosque and they were safe.

His brother said the police evacuated him and his mother in a van but they are safe.

People who are at the mosque say that a younger child has died and they understood the child was aged 4-5.

T

here are reports a person who was driving past was shot.