Officials in Pakistan say they fear more than a thousand people may have been killed in the powerful earthquake that shook South Asia overnight. The quake has also caused severe damage in India and Afghanistan. In Islamabad in Pakistan, tall apartment buildings collapsed. The earthquake measured 7.6 on the Richter scale.Scores of people are being treated for injuries, and rescuers say they are yet to get to the worst affected areas. Strong aftershocks have also been reported. The U.S Geological Survey said the epicentre of the quake was about 100 km northeast of Islamabad in Pakistan-controlled Kashmir. The quake was just 10 kilometres deep. An aftershock of magnitude 5.9 was felt in the Pakistan capital about an hour after the big quake, causing more panic. Officials say many casualties are expected in outlying areas, but it is difficult to get details because phone lines are down. The area where the quake took place is known for its frequent seismic activity.