A 7.7 earthquake shook Indonesia's northwest island of Sumatra early Wednesday, prompting a brief tsunami warning and sending residents rushing for higher ground. There were scattered reports of injuries, but only minor damage was immediately reported. The quake struck at 5:15 a.m. (2215 GMT) and was centered 125 miles (205 kilometers) northwest of the coastal town of Sibolga in Sumatra at a depth of 19 miles (31 kilometers), the U.S. Geological Survey said. It had earlier said the quake measured 7.8. Indonesia's Meteorology and Geophysics Agency and the Pacific Tsunami Warning Center in Honolulu issued tsunami warnings following the quake, but lifted them two hours later.