At least three people have been reported dead and four injured after a 7.8-magnitude earthquake struck the southern city of General Santos in the Philippines on Monday, AFP reported. The quake collapsed buildings and triggered tsunami warnings across the region.This image from a video shows dust and debris outside a building after a powerful earthquake in General Santos city on the island of Mindanao, Philippines. (AP/PTI Image)A second earthquake of magnitude 6.1 hit the area about two hours after the first quake, according to the USGS.Agripino Dacera, the disaster management chief in General Santos, said the fatalities are still being verified as authorities assess the extent of the damage on the ground.Authorities in the Philippines and Indonesia urged residents to move to higher ground after a tsunami of up to 3 feet struck parts of the Philippine coastlinePhilippine President Ferdinand Marcos Jr. suspended school classes in affected areas of Mindanao and called on residents in coastal areas to evacuate immediately, AFP reported."Move to higher ground now. Do not wait," he said. "Your life is more important than anything left behind."Tsunami warning soundedIndonesia issued tsunami alerts for parts of Kalimantan and Sulawesi, warning that waves as high as three metres could strike the affected areas, AFP reported, citing the national weather agency.Indonesia's disaster agency directed authorities in Manado, Gorontalo and the Sangihe Islands to begin orderly evacuations to higher ground as tsunami concerns mounted.The Philippine Institute of Volcanology and Seismology (PHIVOLCS) said it had monitored tsunami waves of varying heights at six monitoring stations. The agency added that the highest tsunami wave recorded measured 1.4 metres.Separately, Japan issued tsunami advisories for large sections of its Pacific coastline, warning that waves of up to one metre could reach affected areas from 11:30 am local time (0230 GMT).Waves of up to one metre are also expected in parts of Indonesia and Malaysia, where tsunami warnings were issued. No tsunami threat has been reported in Thailand or San Francisco so far.Visuals show buildings collapsingVisuals show buildings collapsing and turning into rubble following the earthquake. A video showed a shopping centre with a Jollibee fast food restaurant reduced to rubble in the province's General Santos City, while a school building that officials said was unoccupied crumpled in another, AFP reported."Lord, it has really collapsed! ... The building has really collapsed!" someone was heard shouting.