BEIJING, Dec. 21 (Xinhuanet) -- A civil emergency was declared in a central New Zealand city Friday after several older buildings collapsed during a 6.6-magnitude earthquake rocked much of the island country Thursday.

    Thursday's quake off New Zealand's east coast caused damage to Gisborne's infrastructure but no serious injuries. At least 10 people were treated for minor injuries, officials said.

    The quake, centered in the Hikurangi undersea trench off North Island, hit at 8:55 p.m. at 25 miles below the surface, the GNS Science geological agency reported. It was centered about 30 miles southeast of the coastal city. The U.S. Geological Survey recorded the quake at magnitude 6.6.

    As part of the emergency ordinance, police cordoned off the city's central business area to make sure no serious casualties occurred in damaged buildings, senior sergeant Moira Brown of Gisborne police said early Friday.

    "Our role is to cordon the area and prevent everybody, including shop owners and retailers from going into that CBD (central business district) till buildings and structural damage have been checked by engineers," Brown said.

    "We have got a lot of damage and are still assessing the situation," police inspector Waata Shepherd said. "Some roofs have collapsed. We are still trying to ascertain the amount of damage."

    Power lines were down in some areas, and the quake had left a huge hole in one of Gisborne's main roads, he added.

    Ministry of Civil Defense and Emergency Management spokesman Vince Cholewa confirmed that three buildings collapsed. "As far as we are aware, there are no injuries in those buildings," he said.

    (Agencies)