Rescue workers pulled victims, some screaming in pain, from the heavy rubble of buildings felled by a powerful earthquake that killed at least 531 people. The death toll was expected to rise, according to AP. The brunt of Wednesday's 7.6-magnitude earthquake, which originated in the sea off Sumatra island, appeared to have been borne by Padang town where 376 people were killed. Four other districts accounted for the remaining deaths. The region was jolted by another powerful earthquake Thursday morning, causing damage but no reported fatalities. More than 500 buildings including hotels, schools, hospitals and a mall were destroyed or damaged in Padang. Thousands of people were still believed to be trapped in the rubble, said Rustam Pakaya, head of the Health Ministry's crisis center. Workers used backhoes to shift debris. «Oh God, help me! help me!» Friska Yuniwati, a 30-year-old woman, screamed in pain, as she was carried to an ambulance in downtown Padang. She had been pulled out minutes earlier from the rubble of a house, her face covered in bruises and eyes shut. John Lee, a Singaporean guest at the flattened Maryani hotel, was pulled free by rescue workers who heard his cries for help. He had been trapped for 25 hours with a broken leg. Padang's state-run Djamil Hospital was overwhelmed by the influx of victims and families. Dozens of injured people were being treated under tents outside the hospital, which was itself partly damaged. President Susilo Bambang Yudhoyono pledged to do «everything we can» to help the victims. «Let's not underestimate (the disaster). Let's be prepared for the worst,» Yudhoyono said in Jakarta before flying to Padang, a coastal city of 900,000 and capital of West Sumatra province. A total of 531 people were confirmed dead and 440 were seriously injured, the Social Affairs Ministry's crisis center said. UNICEF said tens of thousands of people had been made homeless, one third of them children. «The needs of thousands of children are vast and urgent. They must have access to clean water, shelter,» Angela Kearney, the U.N. body's Indonesian chief, said in a statement.