New Zealand ? A strong earthquake struck New Zealand on Thursday night, collapsing at least three older buildings in one coastal city on North Island, sparking small fires and forcing authorities to declare a state of emergency there.

Sixteen minor injuries were reported in the port city of Gisborne, which was hit hardest by the quake and suffered the most property damage, although it was felt all over the country, officials said.

The magnitude-6.8 quake was centered in the Hikurangi undersea trench off North Island, 25 miles below the surface, and about 30 miles southeast of Gisborne, the GNS Science geological agency reported.

The temblor did not trigger a tsunami warning at the Pacific Tsunami Warning Center in Hawaii.