New Zealand - The quake which hit Christchurch on Tuesday was centred 10km south-east of the South Island city and struck at 12:51pm.
Police have confirmed fatalities at several locations in the city, including two buses crushed by falling buildings.
Police said other reports include multiple building collapses, fires in buildings in the central city and persons reported trapped in buildings.
Several aftershocks struck the city during the afternoon, with the largest aftershock measured at 5.7 on the Richter scale, at 1:04pm.
New Zealand National Civil Defence Controller David Coetzee said the damage is worse than the 7.1-magnitude quake on 4 September last year.
People have thronged onto the streets of the city center. There are fresh piles of rubble everywhere.
Residents in Christchurch were being asked to stay off the roads to allow emergency services to get through.
The quake was centred in the town of Lyttelton. Fire service said 60 percent of Lyttelton's buildings in the main road, London Street, have fallen.
The military is helping with the search and rescue operation, with the navy vessel HMS Canterbury in port and the army also helping. Port Lyttelton and the Lyttelton Tunnel are closed.
Christchurch Airport is closed, and power is out to about 80 percent of Christchurch.
Christchurch Mayor Bob Parker has declared a local state of emergency.
New Zealand Prime Minister John Key called an emergency Cabinet meeting on Tuesday afternoon.
