Christchurch, New Zealand is extending its post-earthquake state of emergency for another week after a strong aftershock early Wednesday caused more damage.

The 5.1 magnitude aftershock knocked out power to parts of the city and caused loose material from already damaged buildings to tumble to the ground.

One Christchurch resident called Wednesday's jolt very sharp, sudden, and scary.

It was also one of the strongest of the hundreds of aftershocks that have hit New Zealand since Saturday's devastating 7.1 quake.

Prime Minister John Key says it was a miracle no one was killed in Saturday's quake. But roads, bridges, and hundreds of buildings were seriously damaged.

Some information in this story was provided by AFP.