New Zealand Prime Minister Jacinda Ardern has described the deadly shootings at two Christchurch mosques as one of the country’s “darkest days.” She went on to confirm that 40 people had been killed by gunmen who stormed into two crowded mosques on Friday, the holiest of days for Muslims. Police Commissioner Mike Bush later updated the death toll to 49.

“Clearly, what has happened here is an extraordinary and unprecedented act of violence,” Ardern said in an address to a shocked nation after a gunman opened fire inside the Masjid al Noor mosque.

“Many of those who will have been directly affected by this shooting may be migrants to New Zealand, they may even be refugees here,” she said. “They have chosen to make New Zealand their home, and it is their home. They are us. The person [or persons] who has perpetuated this violence against us is not.”

Ardern identified one of the gunmen as Australian national Brenton Tarrant. She said he had two accomplices but that a fourth person arrested today was not connected to the shootings.

News reports characterized the mosque shootings as the deadliest incident in New Zealand’s history. Previously, the Aramoana massacre claimed the lives of 13 people in 1990.

Video live-streamed on Facebook and shared with media outlets appeared to show a gunman walking through the Al Noor mosque and opening fire on people inside the building using an assault rifle.

The Masjid al Noor in central Christchurch was filled with worshippers when the attack happened, as was the second mosque in suburban Linwood.

“[We] are aware there is extremely distressing footage relating to the incident in Christchurch circulating online,” New Zealand police said in a Twitter post. “We would strongly urge that the link not be shared. We are working to have any footage removed.”

Earlier, armed officers were deployed after receiving reports of shots fired at the centrally-located mosque at 1:40 pm local time. Authorities described it as a “serious ongoing firearms incident.”

Citing a witness named Len Peneha, the Associated Press said a man dressed in black entered the mosque and then heard dozens of shots, followed by people running out in terror.

Peneha, who the Associated Press said lived next door to the mosque, said the gunman ran outside, dropped what appeared to be a semi-automatic weapon in the driveway of his house, and fled before police and emergency services arrived.

“I saw dead people everywhere. There were three in the hallway, at the door leading into the mosque, and people inside the mosque,” Peneha said. “It’s unbelievable nutty. I don’t understand how anyone could do this to these people, to anyone. It’s ridiculous.”

Commissioner Bush said in a public statement that all Christchurch schools had been “placed into lockdown.” It was later lifted more than four hours later. “[We] can now confirm the lockdown of schools throughout Christchurch has been lifted,” New Zealand Police said in a statement.

Law enforcement officers also found a number of improvised explosive devices in the gunmen’s cars.

In a separate statement, Australia’s Prime Minister Scott Morrison confirmed that one of those arrested was an Australian citizen. He described the suspected attacker as an “extremist right-wing violent terrorist.”

Morrison had earlier tweeted: “I’m horrified by the reports I’m following of the serious shooting in Christchurch, New Zealand. Our thoughts and prayers are with our Kiwi cousins.”