A magnitude 7.8 earthquake centered at sea shook part of the southern Philippines early Monday, causing damage in a key coastal city, knocking down power and setting off 1-meter (3-foot) tsunami waves along nearby coasts, officials said. President Ferdinand Marcos Jr. asked people to immediately go to higher ground in Philippine areas vulnerable to a tsunami, and Indonesian and Malaysian authorities also issued warnings to their nearby coastal areas. There were no immediate reports of casualties, and it was not clear if people were trapped or injured in the collapse of at least one small building in General Santos, a tuna-processing city of more than 700,000 people that is also a commercial hub in the south. The strongest earthquake to hit the Philippines this year was was centered at sea about 13 kilometers (8 miles) southwest of General Santos and was caused by movement in the Cotabato Trench at a depth of 10 kilometers (6.2 miles), according to the Philippine Institute of Volcanology and Seismology. It struck at 7:37 a.m., the institute's director, Teresito Bacolcol said.