( CNN ) -- Officials declared a state of emergency Saturday after a powerful predawn earthquake struck near Christchurch , New Zealand , sending people into the streets as windows exploded , water mains broke and buildings crumbled . No deaths were immediately reported . The Christchurch City Council declared a state of emergency in response to what it called `` significant damage , '' just hours after the 7.0-magnitude earthquake rattled residents . The order allows authorities to force evacuations and prohibit entry into areas believed unsafe . Officials in Selwyn , a rural district near where the quake hit , also declared a state of local emergency . A curfew from 7 p.m. to 7 a.m. was in place , and the army was assisting local police to ensure there is no looting . Roughly 100 people were being treated for minor bumps and cuts after the strong quake , hospital officials said . Two people suffered more serious injuries . `` The house felt like it was on wheels , like it was rolling around on marbles , '' resident Hadlee Wright told CNN 's Rick Sanchez . Pictures that Wright took of the city before daybreak showed collapsed buildings and streets littered with bits of brick and rock . The facade of one structure was almost entirely torn off . Power was out in the northwest part of the city , while water and sewage services have been affected in several regions , the Christchurch Civil Defense Group said in a statement . Roads were also damaged . Images taken by Jimmy Le Comte , and sent to CNN 's iReport , showed flooding in New Brighton , a Christchurch suburb . In one , a giant crack cuts across a road . 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 with a population of some 386,000 people on the east coast of South Island . An aftershock with a magnitude of 5.7 struck not far from the epicenter about 20 minutes later , the survey said . A man in his 50s was hit by a falling chimney , while another suffered serious injuries after being cut by glass , said Michele Hider , a spokeswoman with Christchurch Hospital . Sebastian Koga , a hospital neurosurgeon , said roughly 100 people were being treated for minor injuries . He was not aware of any deaths . `` We 've had a flood of lacerations and minor head injuries , but nothing that could not be handled , '' Koga said . Civil Defense Minister John Carter said the country 's prime minister is headed to Christchurch to assess the earthquake damage . `` We do n't know entirely what level of issues we 're dealing with at the moment . We 're still getting reports on it , but it has been extensive , '' Carter told CNN affiliate TVNZ . `` We were lucky that the impact on the people from a death point of view has not been what it could have been under normal circumstances . '' The earthquake struck at 4:35 a.m. Saturday ( 12:35 p.m . ET Friday ) , when few people would have been out and about . Police said there was some initial looting activity , but that it was quickly brought under control . 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 . Reinier Eulink , general manager of the Holiday Inn in Christchurch , said there is 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 , Eulink added . People were milling around in the hotel lobby , trying to get warm during the chilly Southern Hemisphere winter . The quake was 7.5 miles deep , according to the U.S. Geological Survey . The Pacific Tsunami Warning Center said the event is not likely to generate a tsunami . Prime Minister John Key told CNN affiliate TVNZ it would likely be some time before the full cost of the quake could be calculated . He sought to reassure residents . `` We 're not going to let Christchurch suffer this great tragedy on its own , '' said Key . CNN 's Nick Valencia , Mark Bixler , Joe Sterling and Katy Byron contributed to this report .
NEW : Prime minister says government will not abandon Christchurch . Two people are being treated for serious injuries . A 7.0-magnitude earthquake hit the east coast of the South Island early Saturday . Roads and buildings were damaged .