Shootings at two mosques in the New Zealand city of Christchurch on Friday resulted in at least 49 fatalities and the detention of three armed suspects, one charged with murder, in what Prime Minister Jacinda Ardern called a terrorist attack.

As news of the tragedy broke, video also surfaced on social media of a gunman opening fire inside one of the mosques.

Authorities say the planned attacks happened at two mosques in the city. Police also defused explosive devices found in a car. More than 45 people were being treated for gunshot injuries at a nearby hospital.

A man who claimed responsibility for the shootings left a manifesto, saying he was a racist who had been planning the attack for two years.

Who are the suspects?

Australian police have identified the shooter as Brenton Tarrant — a white, 28-year-old Australian-born man, according to the New Zealand Herald.

Tarrant briefly appeared at a district court in Christchurch after the shooting, where one charge of murder was presented. District Court Judge Paul Kellar ordered Tarrant to return to court on April 5.

After Tarrant had left, Kellar said it would be "reasonable to assume" there will be other murder charges brought against Tarrant.

Friday night, police said three males and one female had been detained. Police later said one of the arrests didn't relate to the shootings.

Authorities said none of the detained had been on any watch list.

A man who claimed responsibility for the shootings left an anti-immigrant manifesto and said he was a 28-year-old white Australian and a racist.

Attack live-streamed

A 17-minute video posted to social media shows a gunman opening fire in the Masjid Al Noor mosque, an apparent livestream of the attack from a helmet camera.

It shows him arming himself and walking into the mosque, immediately shooting a person in the doorway. His weapon was covered in white-supremacist graffiti.

In an over 70-page manifesto posted to various sites including Twitter and Scribd that appeared to belong to the gunman, he identified himself as a 28-year-old white man born in Australia.

More:Christchurch gunman appeared to live-stream his attack in 17-minute Facebook video

How many people were killed?

Friday evening local time, authorities said at least 49 people were killed and dozens were being treated for gunshot injuries, ranging from minor to critical.

Where did the shootings happen?

Police have confirmed two shooting locations: One at Linwood Avenue and one at Deans Avenue in the city.

Witness Len Peneha reported seeing a gunman enter Masjid Al Noor mosque on Deans Avenue at about 1:45 p.m.

Police also said there was a second shooting at the Linwood Masjid Mosque.

What have witnesses said?

Len Peneha, a witness of the Masjid Al Noor shooting who lives next to the mosque, said he saw a man dressed in black enter the building. He reported hearing dozens of shots, followed by people running from the mosque in terror.

When he later went to the mosque to help, he reported finding carnage inside: "I saw dead people everywhere. There were three in the hallway, at the door leading into the mosque, and people inside the mosque," he said.

Near the Linwood Masjid Mosque shooting, Mark Nichols reported hearing about five gunshots, the New Zealand Herald reports. Nichols said he saw two injured people being carried out on stretchers past his automotive shop and that both people appeared to be alive.

More:Christchurch mosque shooting adds to growing list of attacks in places of worship

What's the response?

Ardern said it was "one of New Zealand’s darkest days" in a news conference and called the attack one of “unprecedented violence."

On Saturday, Ardern said the country's gun laws will change in response to the tragedy. She did not specify how the laws will be changed.

President Donald Trump condemned the attacks as a "horrible massacre."

White House press secretary Sarah Sanders issued a statement Friday, saying “the United States strongly condemns the attack in Christchurch. Our thoughts and prayers are with the victims and their families. We stand in solidarity with the people of New Zealand and their government against this vicious act of hate.”

The Council on American-Islamic Relations held a press conference ahead of Friday prayer in the U.S., urging worshippers to "not be afraid" and "not abandon your mosques." The Washington-based civil rights organization also urged Trump to specifically speak out against white supremacy.

Egypt's Al-Azhar University, known for Sunni Islamic studies, said in a statement the attacks are “a dangerous indicator of the dire consequences of escalating hate speech, xenophobia, and the spread of Islamophobia."

The Los Angeles Police Department said Thursday night it was providing extra security to mosques in L.A.

In a live-stream of the shooting, the gunman asked viewers to subscribe to PewDiePie, a video stream by controversial YouTuber Felix Kjellberg. Kjellberg tweeted a statement saying he feels “absolutely sickened having my name uttered by this person.” He offered his condolences to those affected by the shooting.

When was the last mass shooting in New Zealand?

Mass shooting events are rare in New Zealand. The last one occurred in 1990 and claimed 13 lives in addition to the killer, the Guardian reports.

In 2017, the New Zealand police reported a total of 35 murders in the country, most didn’t involve a gun. That year in the U.S. there were over 17,200 murders in the U.S. in 2017, according to the FBI.

Guns are not uncommon in New Zealand though, as Swiss nonprofit Small Arms Survey reports 1.2 million registered firearms in the country in 2017.

More:Mass shootings are rare in New Zealand

Contributing: Kristin Lam, USA TODAY; Associated Press