Christchurch's main business district was put under a 12 hour curfew (from 3 a.m. ET), with police cordoning off the area to deter looters.
Authorities there warned residents to boil their water before drinking, hoping to check for disease outbreaks. They fear that sewage lines may be broken or leaking underground, allowing contaminated water to enter the drinking system.
Power is gradually being restored but there were still sporadic outages and brownouts reported across the city and surrounding areas,
TVNZ reporter Max Bania described a city and people still in shock from the powerful quake, and shaken by continuing aftershocks.
He told CNN that residents described feeling like they were being thrown into a cement mixer during the magnitude 7.0 quake.
"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.
The Christchurch City Council declared a state of emergency in response to what it called "significant damage," just hours after the earthquake.
The order allows authorities to force evacuations and prohibit entry into areas believed unsafe. Officials in Selwyn, a rural district near where the quake region, also declared a state of local emergency.
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 it was quickly brought under control.
Roughly 100 people were being treated for minor bumps and cuts after the strong quake, hospital officials said. Two people suffered more serious injuries.
No deaths were immediately reported.
Schools in the area…