A powerful magnitude 7.7 earthquake struck off the coast of Indonesia early Saturday, collapsing buildings and homes, killing at least two people and causing panic in a region prone to deadly quakes. Authorities issued a tsunami warning but later lifted it when Indonesia’s Meteorology, Climatology and Geophysics Agency said monitoring showed no significant sea-level changes that would pose a threat to coastal communities. The US Geological Survey said the quake hit Indonesia’s Flores region with...