Authorities urge coastal residents to move inland or to higher ground following the quake near Flores Island.A powerful magnitude 7.7 earthquake has killed at least five people after it struck off the coast of Indonesia’s Flores Island, causing widespread damage.The United States Geological Survey (USGS) said the quake struck early on Saturday at 5:58am local time (21:58 GMT Friday), with an epicentre about 68 kilometres (42 miles) north-northwest of the city of Ende, in East Nusa Tenggara province. USGS put the depth at 10km (6.2 miles).Three aftershocks followed within half an hour, measuring magnitudes 5.9, 5.6 and 6.1.East Nusa Tenggara police chief Rudi Darmoko said preliminary reports indicated two deaths in Sikka Regency and three in Manggarai Regency as the earthquake caused severe damage and collapsed buildings. Outages in cities and villages have hampered the flow of information and complicated search and rescue efforts, he added.East Nusa Tenggara Governor Emanuel Melkiades Laka Lena told journalists the five people died ⁠from collapsing rubble as they slept.According to officials, the death toll is expected to climb further as emergency teams continue working through the aftermath.Local media footage has shown extensive damage to buildings in the aftermath of the earthquake, with areas around the Maumere region sustaining severe impact.Indonesia’s Meteorology, Climatology and Geophysics Agency (BMKG) issued a tsunami warning for affected coastlines, urging residents to stay away from beaches and riverbanks and move to higher ground. The warning has since been lifted.Extent of damage still ’emerging’USGS estimates suggest more than half a million people on Flores Island, in eastern Indonesia, are likely to have experienced very strong shaking, with moderate to strong shaking felt by several million more people across the wider region.Local authorities said they were continuing to monitor the situation and assess the risk of further aftershocks in the hours ahead.Reporting from the Indonesian capital, Jakarta, Al Jazeera’s Jessica Washington said that the aftershocks could persist for “several days”, according to local weather agencies.In northern parts of the island, residents have been ordered to evacuate, as the extent of the damage is still “emerging”, said Washington. “Many houses have been damaged.”Washington added that local authorities are unable to reach several affected areas, which remain “locked” for first responders and assistance. Authorities have also advised locals to stay away from the shores and buildings, she said.Indonesia, a nation of more than 270 million people spread across roughly 17,000 islands, sits on the Pacific “Ring of Fire” and is one of the world’s most seismically active countries.The same stretch of coastline was struck by a similarly powerful earthquake in December 1992, when the quake and the tsunami it triggered killed more than 2,500 people on Flores.