MANILA -- At least one person was killed and buildings collapsed after a 7.8-magnitude earthquake struck off the southern coast of the Philippine island of Mindanao on Monday morning, according to a police officer in the nearest big city to the epicenter.

"One person was killed and lots of buildings around the city, including a school and some houses, collapsed," General Santos Master Sergeant Robert Dagon told Nikkei Asia, describing the impact of the disaster that struck at 7:41 a.m. local time.

Videos posted to social media claimed to show a school, shops and offices that had crumpled in the city, which is 1,050 kilometers south of the capital Manila. However, it was impossible to immediately verify this.

The quake struck at a depth of 10 kilometers, the German Research Center for Geosciences said. The geophysics agencies of the Philippines and neighboring Indonesia issued tsunami warnings, but there were no reports of significant waves two hours after the disaster. Several 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.