• One man in his late 20s charged with murder
• Three others in custody
• Alleged gunman posted Islamophobic and white nationalist manifesto online

A mass shooting at two mosques in Christchurch, New Zealand , on Friday left at least 49 people dead and the city on lockdown for hours.

It is clear that this can now only be described as a terrorist attack, Prime Minister Jacinda Ardern said at a news conference. From what we know, it does appear to have been well planned. ... 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.

Ardern said that the country had raised its threat level to high following the attacks, which began just before 3 p.m. local time.

At the Deans Avenue mosque, we now know that 41 people have lost their lives, New Zealand Police Commissioner Mike Bush said at a press conference at 9 p.m. local time. And at the Linwood mosque, seven have lost their lives. Of the 40 people who have been treated at Christchurch Hospital, one has now passed.

He described the attack as a well-planned event.

Four people were taken into custody. Bush said one man in his late 20s has been charged with murder and will appear in Christchurch court Saturday morning. The police were still working to determine if and how the other three were involved.

Australian Prime Minister Scott Morrison said one of the people in custody was an Australian citizen .

Asked whether any of the those arrested had been on any security watch lists, Bush said no agencies had any information on these people.

Bush, who called the shooting a very serious and grave situation, said authorities had safely disarmed an improvised explosive device that had been placed on a vehicle and were working to neutralize a second.

He praised local police for some absolute acts of bravery to help apprehend the suspects.

Radio NZ reported that hundreds of people were praying at one of the mosques when the shooting took place.

Witness Len Peneha told The Associated Press she saw a man dressed in black enter the Masjid Al Noor mosque and heard dozens of shots, which sent people running.

I saw dead people everywhere, Peneha said.

Ardern said it was clear that this is one of New Zealands darkest days. She issued the strongest possible condemnation of the ideology of the people who did this and praised New Zealands diversity and compassion on Friday evening.

You may have chosen us, but we utterly reject and condemn you, she said.