Italy hits by 6.6 magnitude earthquake.

A powerful earthquake with a preliminary magnitude of 6.6 on Sunday rocked the same area of central and southern Italy hit by quake in August and a pair of aftershocks last week, sending already quake-damaged buildings crumbling after a week of temblors that have left thousands homeless.

The earthquake was believed to be the strongest to strike the country since 1980. A 6.9-magnitude quake in southern Campania that year killed some 3,000 people and caused extensive damage.

Some 20 people suffered injuries, most of them minor, investigators said. However, numerous buildings that had resisted the previous quakes collapsed. Crews were responding with helicopters as rockslides blocked many roads, the head of Italy's civil protection agency, Fabrizio Curcio, told reporters.