New Zealand Prime Minister Jacinda Ardern said 49 people have been killed and injured in a shooting at a mosque in the center of Christchurch, New Zealand.

New Zealand police tweeted that officers responded to a "serious ongoing firearms incident" around 1:40 p.m. Friday (8:40 p.m. Thursday ET). They said schools in the city had been placed on lockdown and urged people to stay indoors.

Nearly two hours after the initial response, police tweeted that the situation was "serious and evolving."

"Police are responding with its full capability to manage the situation, but the risk environment remains extremely high."

There was no official word on casualties, but witnesses said the Masjid Al Noor mosque was full for Friday afternoon prayers and many people were dead.

Witness Len Peneha told the Associated Press he saw a man dressed in black enter the mosque and then heard dozens of shots, followed by people running from the mosque in terror. Peneha, who has lived next door to the mosque for about five years, said the gunman ran outside, dropped what appeared to be a semi-automatic weapon in Peneha's driveway, and fled before emergency services arrived.

Peneha said he went into the mosque to try and help.

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

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

Zayd Blissett, chairman of the Muslim Association of Marlborough, told Stuff.co.NZ that he received a text the Federation of Islamic Associations of New Zealand (FIANZ) saying "50 shot" at the mosque.

"I'm just heartbroken," he said. "In fact, I'm sitting here crying. This is New Zealand. This can't happen here."

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A third witness, Mohammed Nazir, told TVNZ he saw three women shot and bleeding outside the mosque. He told police that he called the police climbed a wall to escape, leaving his shoes behind in the process.

A witness who declined to give his name told Stuff the gunman was wearing a helmet and fired more than 50 shots.

"He had a big gun and a lot of bullets and he came through and started shooting like everyone in the mosque, like everywhere, and they have to smash the door and the glass from the window and from the small door to try and get out," he said.

The Guardian reported that police had discovered a bomb in a beige Subaru that had crashed in the center of Christchurch, approximately two miles from the mosque. The paper reported that police officers had cordoned off the street and were keeping a safe distance from the vehicle.

Christchurch, located on New Zealand's South Island, is the third-largest city in the country with a population of just over 400,000. It was affected by a devastating earthquake in February 2011, which killed 185 people and triggered the collapse of thousands of buildings across the city.

This is a developing story, check back for more updates.

The Associated Press contributed to this report.