Officials say the earthquake damaged or destroyed 87 buildings and nearly 600 houses and affected more than 170,000 people. [Eloisa Lopez/Reuters]

DAVAO, Philippines (AP) — An offshore magnitude 7.8 earthquake hit the southern Philippines on Monday, killing at least 32 people, injuring more than 200 others mostly in ruined buildings and sending a 1-meter (3-foot) tsunami into nearby coasts.

Several mostly low-rise buildings collapsed or sustained heavy damages in the hard-hit city of General Santos. Tsunami damage was reported in at least one southern coastal village. Smaller waves were measured in Indonesia and Palau and as far away as southern Japan.

In a video shared by Mahayahay Elementary School on social media, school children were seen screaming and crying when an offshore magnitude 7.8 earthquake rocked the southern Philippines early Monday.

The quake also triggered a landslide in Glan, a municipality in the province of Sarangani, that killed 13 villagers, Rene Punzalan, a provincial disaster-mitigation official, told the DZBB radio network. Four other villagers died in Sarangani, he said.

The major earthquake was the strongest to hit the Philippines this year, Teresito Bacolcol, the director of the Philippine Institute of Volcanology and Seismology, said. He warned people to seek advice before returning to damaged buildings and houses, which could collapse due to aftershocks.

The United States, a treaty ally of the Philippines, said it was coordinating with Manila and was ready to support Philippine response efforts. France and New Zealand also expressed support.

“Our pickup truck suddenly jerked and I thought we had a flat tire,” Rod Sosmeña, a regional director of the Office of Civil Defense, told The Associated Press from General Santos, where he was traveling when the quake struck at 7:37 a.m.

“The shaking was very strong and people dashed out of houses into the streets,” Sosmeña said.

Epicenter in sea off Mindanao

More than 100 students in uniforms and a dozen teachers had gathered for a flag-raising ceremony in a coconut tree-ringed grade school compound in the rural town of Malita in Davao Occidental province when the ground shook, turning the first day of school after a two-month summer break into chaos.

“Their excitement on the first day of school turned to trauma,” school principal Rosavel Cachuela told the AP.

Some of the young students screamed in panic and wept but mostly remained seated and still, preventing any injuries, Cachuela said, adding that a motorcycle was damaged when a shed crumbled to the ground.

At least 12 people remained missing in General Santos, a port city of more than 700,000 people and a regional hub for the tuna export industry. Search and rescue teams scrambled to find people who may have been trapped in a supermarket, a warehouse, a grade school, and other small buildings that either collapsed or were severely damaged, officials said.