MANILA -- A 7.8-magnitude earthquake that struck off the southern coast of the Philippine island of Mindanao on Monday has left at least seven people dead and more than 130 injured while also toppling many buildings in the nearest big city to the epicenter, according to a senior disaster management official.

Rod Sosmena, director of the Office of Civil Defense region that covers Mindanao, confirmed the casualty figures in the city of General Santos, about 15 kilometers from the epicenter, to Nikkei Asia and suggested it might well rise as reports are checked and confirmed.

Multiple schools, shops, offices and other commercial buildings sustained damage in General Santos, which is 1,050 kilometers south of the capital Manila, officials said, and videos posted to social media confirmed this.

Damage was also reported in other provinces across Mindanao, including South Cotabato and Davao Occidental.

The quake struck at a depth of 10 kilometers at 7:37 a.m., the German Research Center for Geosciences said. The geophysics agencies of the Philippines and neighboring Indonesia issued tsunami warnings, and waves up to 1.4 meters higher than normal were reported in several areas. The warnings were lifted at 3:20 p.m. local time. A number of aftershocks greater than magnitude-6 were reported.

Neighboring Indonesia also issued a tsunami warning. One woman who lives just outside Manado, the nearest big Indonesian city to the epicenter, said she felt the quake but added, "We're all good and safe."

Philippine President Ferdinand Marcos Jr. ordered the suspension of classes in all schools in affected areas across Mindanao on what was the first day of the country's new school year. "The national government is moving, and we will not leave Mindanao behind," he said in a statement. "I am in constant communication with our regional offices and local chief executives on the ground."

The Philippines and Indonesia -- which sit on the "Pacific Ring of Fire," a seismically active belt stretching from South America to the Russian Far East -- experience hundreds of earthquakes each year.