At least 40 people have been killed after gunmen opened fire in two mosques in the New Zealand city of Christchurch Friday, a coordinated and unprecedented attack that has shocked the usually peaceful nation.

New Zealand Police Commissioner Mike Bush said four people have been taken into custody — three men and one woman — though police cannot assume that there are not other suspects at large.

The shootings occurred at the al Noor mosque on Deans Avenue and Linwood Masjid in Linwood, both in Christchurch’s city center.

“We are unsure if there are any other locations outside of that area that are under threat,” Bush said, adding that the two locations were on lockdown.

Multiple improvised explosive devices were attached to vehicles as part of the attack, Bush told reporters. These had been “made safe by the defense force.”

“This goes to the seriousness of the situation,” he said.

Police were still treating the incident as ongoing into Friday evening local time and urged Christchurch residents to stay indoors and monitor the police website and social media.

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The situation was also considered as to limited to Christchurch and Bush asked “anyone who was thinking of going to a mosque anywhere in New Zealand today not to go. To close your doors until you hear from us again,” he said.

All mosques nationwide have been asked to shut their doors.

In a press conference, New Zealand’s Prime Minister Jacinda Ardern described the attack as “one of New Zealand’s darkest days.”

“What has happened here is an extraordinary and unprecedented act of violence,” she said, adding that the attackers have “no place in New Zealand.”

“For now my thoughts and I’m sure the thoughts of all New Zealanders are with those who have been affected their families,” she said.

Police said they have mobilized every national police resource to respond to the incident.

One of the shooters an Australian citizen

Authorities said that they “will not be discussing the offenders’ possible motivations or the causes of this incident” at this stage.

However, in a social media post just before the attack, an account that is believed to belong to one of the attackers posted a link to an 87-page manifesto that was filled with anti-immigrant, anti-Muslim ideas and explanations for an attack. The manifesto was not signed.

Australian Prime Minister Scott Morrison confirmed that at least one of the individuals taken into custody is an Australian born citizen.

He called shooting as being at hands of a “extremist right wing, violent terrorist” at a press conference Friday.

CNN has not been able to independently confirm any information about any of the attackers at this stage.

Gunman opened fire ‘for ten to 15 minutes”

Armed police were deployed after first receiving reports of the shootings at 1:40 p.m. Friday local time. It is the busiest day for many mosques around the world when Muslims convene for Friday prayers.

Speaking to CNN, witness Mohan Ibn Ibrahim said he was inside the mosque when the shooting began and that he heard the gunman “continuously shooting for ten to 15 minutes.”

“It’s a big mosque and there were more than 200 people inside. The gunmen came from the backside. Gunshots went on for a long time. We had to jump the wall to escape. I saw lots of broken glass and bricks on the backside of the mosque,” he said.

“I came to the street I saw one person got shot on his chest,” he said, adding that the ambulance and police then arrived on the scene.

He said that he had a friend in another mosque in the area had told him a gunman had opened fire there as well and five people were dead.

“I could not contact two of my friends who are in the mosque as well,” he said.

A spokesperson at Christchurch Hospital told CNN that “multiple” casualties had been sent there, but did not confirm the number.

One witness, who did not want to be named, said he was driving by the scene and saw a man with a “with his 3 or 4-year-old daughter” who had been shot in the back.

“He was screaming like get her to the hospital and the ambulance couldn’t come in until it was secured so I just got my truck and loaded up him, and his daughter, and this other guy had been shot in the leg, and took them to the hospital,” he said.

One man outside the mosque said that he prayed that the gunman would “run out of bullets.”

“I was thinking that he must run out bullets you know, so what I did was basically waiting and praying to God, oh God please let this guy run out of bullets,” he said. He said a man told him to remain still when the gunman shot the man “straight in the chest.”

Police are aware of a video shared online and not verified by CNN that purports to show a gunman walking into an unnamed mosque and opening fire. They have asked social media users to stop sharing graphic footage circulating online relating to the incident in Christchurch.

“We would strongly urge that the link not be shared. We are working to have any footage removed,” the New Zealand police said.

In a statement, a spokesperson for Facebook New Zealand, Mia Garlick, said videos that appeared to show the Christchurch shootings were quickly taken down.

“New Zealand Police alerted us to a video on Facebook shortly after the livestream commenced and we removed both the shooter’s Facebook account and the video. We’re also removing any praise or support for the crime and the shooter or shooters as soon as we’re aware,” she said.

Christchurch was put on lockdown with all schools and council buildings shut and roads closed across the city.

By 6 p.m. local time New Zealand police said the lockdown on schools had been lifted.

Police can now confirm the lock down of schools throughout Christchurch has 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. (CNN)