India, Aug. 16 -- A powerful magnitude 7.7 earthquake struck off the coast of Indonesia early Saturday, killing at least 47 people, collapsing buildings and causing panic in a region prone to deadly quakes. Authorities said dozens more residents were injured and warned that the death toll would almost certainly rise.

Authorities issued a tsunami warning and urged coastal residents to move to higher ground, but later lifted the warning when Indonesia's meteorological agency said monitoring showed no significant sea-level changes that posed a threat to coastal communities. Some smaller tsunamis were reported.

The US Geological Survey said the quake hit eastern Indonesia's Flores region at a depth of 10 kilometres (6 miles) at 5:58 am loca...