New Zealand police say the death toll has risen to 49 following an attack on two mosques.

Reports say gunmen entered two mosques and began shooting in New Zealand’s city of Christchurch on Friday killing at least 40 people.  

New Zealand’s Prime Minister Jacinda Ardern told a news conference that 20 others were in a critical condition after the “terrorist” attack. 

Police Commissioner Mike Bush said four suspects were in custody, three men and a woman.

Reports say a man entered a mosque with an automatic weapon and began firing.

“A gunman dressed in black with a helmet carrying a machine gun came into the back of the mosque and started firing into the people praying there,” said an eyewitness.

Police confirmed a second shooting occurred at the Linwood mosque during Friday prayers in the South Island city, but no details were immediately available.

“This is, and will be, one of New Zealand’s darkest days,” said Ardern.

Authorities have not described the scale of Friday’s shootings but urged people in central Christchurch to stay indoors. 

Police warned worshippers not to visit mosques “anywhere in New Zealand”. A lockdown imposed throughout Christchurch was called off at about 05:00 GMT. 

Australian Prime Minister Scott Morrison said one of the suspects was an Australian national, calling him an “extremist, right-wing, violent terrorist”. 

A witness Len Peneha said he saw a man dressed in black enter the Masjid Al Noor mosque and then heard dozens of shots, followed by people running from the mosque in terror.

He said he also saw the gunman flee before emergency services arrived.

Peneha who lives next to the mosque said he went into the building to try and help.

“I saw dead people everywhere,” he added

One man in the mosque, with blood stains all over his clothes, said he hid under a bench as the shooting took place. He said about 50 people were inside the building. 

Clarke said some worshippers managed to escape through windows and doors but “many people had been hit, some as young as 16”.  

About 10 to 15 people were seen outside the mosque, “some alive, some dead”, he said. 

“It was unbelievable. I saw about 20 people, some dead, some screaming,” one eyewitness told local press.

“I saw on the floor so many bullet shells, hundreds. I saw one guy trying to run out and he was shot dead.”

One of the gunmen shared a livestream of the attack on Facebook and posted content on Instagram.

Facebook said it has taken down the video and was removing praise for the gunman.

“Police are aware there is extremely distressing footage relating to the incident in Christchurch circulating online”.

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

There were reports racist literature was left behind at the scene denouncing “invaders”.

Commissioner Bush said local police officers apprehended the four suspects.

“I won’t assume there aren’t others but I don’t have any information to that effect,” Bush told a press conference.

He said a number of bombs were detected and neutralised on the attackers’ automobiles.

“There were a few reports of IEDs strapped to vehicles which we were able to secure,” he said, referring to improved explosive devices. 

Asked by reporters whether police considered Friday’s carnage a “terrorist attack”, Bush said an investigation was underway.