WELLINGTON, New Zealand — A 6.3-magnitude earthquake rocked the southern New Zealand city of Christchurch Tuesday, killing dozens, collapsing buildings and cracking streets.

Prime Minister John Key said at least 65 had died as a result of the disaster and told reporters that the death toll was expected to rise further. "It is a just a scene of utter devastation," he added.

Television footage showed streets strewn with bricks and shattered concrete. Sidewalks and roads were cracked and split, and hundreds of dazed, screaming and crying residents wandered as sirens blared throughout the city.

Bodies were being pulled from rubble, others lay in the streets. Water mains burst, causing extensive flooding.

New Zealand's 3 News television station said that by 10:30 p.m. Tuesday local time (4:30 a.m. ET) that there were reports of at least 125 people being rescued.

However, it added that Mayor Bob Parker estimated that more than 100 people were still trapped at six different locations with possibly more in individual homes. Parker said earlier that he had been "thrown quite a distance" by the quake.

The TV station said the 33rd aftershock hit at 10:18 p.m. local time (4:18 a.m. ET).

It was the second quake to hit the city in five months, and New Zealand's deadliest natural disaster for 80 years. In 1931, a quake in the North Island city of Napier killed 256 people.

"We may well be witnessing New Zealand's darkest day...The death toll I have at the moment is 65 and that may rise," Key told local TV. "It's hard to describe. What was a vibrant city a few hours ago has been brought to its knees."

Key held an emergency Cabinet meeting then rushed to the stricken city to observe the scene.

He said eight or nine buildings had collapsed, and that officials were working as fast as they could to free those who were trapped.

Christchurch's historic Cathedral of the Blessed Sacrament was left half-collapsed with the remaining part of the building filled with cracks.

The New Zealand Herald newspaper reported that 30 million tons of ice broke free from the Tasman Glacier in Aoraki Mt Cook National Park, sending an 11-foot wave crashing into boats on Terminal Lake.

Trapped on 12th floor
New Zealand police said in a statement that there were reports of multiple deaths, including a report that two buses had been crushed by falling buildings. The police statement said there were other reports of fires burning.

Office worker Gary Moore said he and 19 other colleagues were trapped on the twelfth floor of their building after the stairwell collapsed in the quake. He did not know if people on other floors were trapped.

"We watched the cathedral collapse out our window while we were holding onto the walls," Moore said. "Every aftershock sends us rushing under the desks. It's very unnerving but we can clearly see there are other priorities out the window. There has been a lot of damage and I guess people are attending to that before they come and get us."

The multistory Pyne Gould Guinness Building, housing more than 200 workers, collapsed and an unknown number of people were trapped inside.

Television pictures showed rescuers, many of them office workers, dragging severely injured people from the rubble. Many had blood streaming down their faces. Screams could be heard from those still trapped.

A woman trapped in one of the buildings said she was terrified and waiting for rescuers to reach her six hours after the quake.

"I thought the best place was under the desk but the ceiling collapsed on top, I can't move and I'm just terrified," office worker Anne Voss told TV3 news.

John Gurr, a camera technician who was in the city center when the quake hit, said he was outside the cathedral when it collapsed.

"The whole front has fallen down and there were people running from there. There were people inside as well," he said.

"A lady grabbed hold of me to stop falling over ... we just got blown apart. Colombo Street, the main street, is just a mess ... There's lots of water everywhere, pouring out of the ground," Gurr added.
'Horrific'
Nathanael Boehm, a web designer, said he was standing near a tram track when the quake struck, sending the eaves of buildings cascading onto the street below.

"It was horrific. People were covered in rubble, covered in several tons of concrete," Boehm said, adding that he believed some of them had been crushed to death.

There were bodies lying in the streets, the New Zealand Herald reported.

"We've had friends in town call us and say there are just bodies lying around," Jaydn Katene told the paper. "Lots of dead bodies outside shops just lying there just covered in bricks.

"When it hit we were knocked to our feet," Katene continued. "Everything in the house fell down, nothing was left still standing. The roads are completely torn up; sewage coming up and flooding. It's crazy."
Slideshow: 6.3 quake rocks New Zealand (on this page)

Christchurch Hospital saw an influx of injured residents.

"We've had a lot of people at the emergency department ... a significant number, a lot of major injuries," said David Meates, the chief executive of the Canterbury Health Board.

"They are largely crushes and cuts types of injuries and chest pain as well," he said, adding some of the more seriously injured could be evacuated to other cities, where hospitals had been put on alert and were preparing to accept casualties.

The epicenter of the quake was located in the "worst possible location" for city residents, New Zealand's GeoNet Center data manager Kevin Fenaughty told the New Zealand Herald.

The U.S. Geological Survey said the temblor, which struck just before 1 p.m. local time (7 p.m. ET Monday), was centered 3 miles from the city at a depth of 2.5 miles.

Christchurch has been hit by hundreds of aftershocks since the 7.1 magnitude earthquake struck on Sept. 4 last year, causing extensive damage and a handful of injuries, but no deaths. That quake was seated deeper in the earth's crust.

Unlike last year's tremor, which struck early in the morning when streets were virtually empty, the streets, shops and offices in the city of almost 400,000 were thronging with people when the shallow tremor struck Tuesday.

New Zealand Herald reporter Jarrod Booker said the shaking lasted approximately a minute and was extremely violent — rocking buildings back and forth.

Evacuation order
Parker, the mayor, declared a state of emergency and ordered people to evacuate the city center.

"Make no mistake — this is going to be a very black day for this shaken city," he said when asked about possible deaths.

He told Radio New Zealand the quake was as violent as the one in September and said he had been knocked off his feet.

"I got down onto the street and there were scenes of great confusion, a lot of very upset people," he said. "I know of people in our building who are injured and I've had some reports of serious injuries throughout the city."

City councilman Barry Corbett was on one of the top floors of the city council building when the quake struck.

"When the shaking had stopped I looked out of the window, which gives a great view onto Christchurch, and there was just dust," he said. "It was evident straight away that a lot of buildings had gone."

The city is considered a tourist center and gateway to the South Island.

New Zealand sits on the Pacific "ring of fire" — an arc of earthquake and volcanic zones stretching from Chile in South America through Alaska and down through the South Pacific.

It records more than 14,000 earthquakes a year — but only about 150 are felt by residents, and fewer than 10 a year do any damage.