WELLINGTON, New Zealand – A powerful 7.1-magnitude earthquake struck much of New Zealand’s South Island early today and caused widespread damage, but there were just two reports of serious injuries. Looters broke into some damaged shops in Christchurch, police said.

The quake, which hit 19 miles west of the southern city of Christchurch according to the state geological agency GNS Science, shook a wide area, with some residents saying buildings had collapsed and power was severed. No tsunami alert was issued.

GNS Science initially reported the quake as magnitude 7.4 but later downgraded it after re-examining quake records. The U.S. Geological Survey measured the quake at 7.0.

Christchurch Mayor Bob Parker declared a state of emergency four hours after the quake rocked the region, warning people that continuing aftershocks could cause masonry to fall from damaged buildings.

The emergency meant parts of the city would be closed off and some buildings closed as unsafe, he said.

Minister of Civil Defense John Carter said a state of civil emergency was declared as the quake was “a significant disaster,” and army troops were on standby to assist.

Parker said the “sharp, vicious earthquake has caused significant damage in parts of the city … with walls collapsed that have fallen into the streets.”

Chimneys and walls had fallen from older buildings, with roads blocked, traffic lights out and power, gas and water supplies disrupted, he said.

“The fronts of at least five buildings in the central city have collapsed and rubble is strewn across many roads,” Christchurch resident Angela Morgan told The Associated Press.

Christchurch fire service spokesman Mike Bowden said a number of people had been trapped in buildings by fallen chimneys and blocked entrances, but there were no reports of people pinned under rubble. Rescue teams were out checking premises.

Christchurch Hospital said it had treated two men with serious injuries and a number of people with minor injuries.

One man was hit by a falling chimney and was in serious condition in intensive care, and a second was badly cut by glass, hospital spokeswoman Michele Hider said.

Christchurch police reported road damage in parts of the city of 400,000 people, with a series of sharp aftershocks rocking the area. Police officers cordoned off some streets where rubble was strewn about. Video showed parked cars crushed by heaps of fallen bricks, and buckled roads.