A powerful earthquake that struck New Zealand on Saturday caused "a lot of damage," though there are no reports of serious injuries or major damage, an emergency official said.

"It was like a freight train running through the house," said Chris Monroe, operations manager for the New Zealand Fire Service.

The quake had a magnitude of 7.0, down from an initial assessment of 7.4, the U.S. Geological Survey said. It struck about 35 miles from Christchurch, a city of about 386,000 people.

An aftershock with a magnitude of 5.7 struck not far from the epicenter about 20 minutes later, the survey said.

Power was out to much of Christchurch "because of extensive damage there," Radio New Zealand reported.

One person said the quake "turned his house upside down, with crockery breaking," the station reported, citing Orion, a power company. Sewer lines and water pipes have ruptured, a company spokesman told the station.

"Structural damage to houses and broken glass have been reported throughout Christchurch," the station said.

A man who was at the international airport in Christchurch described the scene.

"The entire terminal started shaking," he said. "I knew it was an earthquake.There was not much you could do at that point."

Authorities evacuated the airport, he said, adding that he saw minor damage.

"We’ve just had a terrible earthquake," said Paula May, a Christchurch resident. "We have no power. Lots of stuff in the house is all over the floor. All the power is down, so I can’t see anything. There’s no power in the town."

She said that in her house, "we’ve got everything down in the rooms," and that although it appears there are buildings down in the region, such as old stone masonry-type structures, "everyone I know seems to be OK."

Tim Dower, a New Zealand journalist, said it’s fortunate the earthquake struck in darkness and not daytime, when people would have been out and about.

"When one of this magnitude comes along, people certainly feel it, particularly when it’s shallow," he said.

There have been reports, he said, of facades and buildings collapsing, cars damaged and flooding in homes.

"We don’t have any reports of significant injuries at this stage."

A person who answered the phone at the George hotel in Christchurch said that "we are cleaning up at the present moment" but wouldn’t disclose any more detail.

Reinier Eulink, general manager of the Holiday Inn in Christchurch, said there’s damage around the hotel corridors and "big cracks in the walls."

"It was a big big long jolt, and the building moved a lot," he said. The 13-floor building, with about 150 rooms, was about 40 percent occupied, and he estimated that 80 or more people were staying at the hotel at the time.

Power was knocked out, but emergency power came on. People were milling around in the hotel lobby, trying to get warm during the chilly Southern Hemisphere winter.

"My room is totally upside down," Eulink said.

A Christchurch Hospital shift manager said there are injuries and damage from the quake.

"We are in emergency planning at the moment," he said.

The quake was 7.5 miles deep. It struck at 4:35 a.m. Saturday (12:35 p.m. ET Friday), the survey reported.

The quake is not likely to generate a tsunami, according to the Pacific Tsunami Warning Center.