Powerful 6.7 magnitude earthquake rocks southern Philippines

A strong magnitude 6.7 earthquake has shaken the southern Philippines, the US Geological Survey said, causing people to flee buildings and part of a shopping mall ceiling to collapse.

No tsunami threat was issued after the quake struck off Sarangani province on the main southern island of Mindanao at a depth of 78 kilometres (48 miles) at 0814 GMT, the USGS said in a statement on Friday.

There were no immediate reports of casualties but the quake was felt across a wide area of the mountainous island.

A photo shared on Facebook showed a collapsed ceiling inside a shopping mall in General Santos City, less than 100 kilometres from the epicentre.

A video showed terrified shoppers in another mall in the same city hiding under fast-food restaurant tables and screaming as the building shook and pieces of the ceiling fell.

About 30 students at a nearby high school were treated for breathing difficulties due to panic following the quake, said Adrian Imbong, an emergency medical services worker in General Santos City.

No 'substantial damage'

Quakes are a daily occurrence in the Philippines, which sits along the Pacific "Ring of Fire", an arc of intense seismic as well as volcanic activity that stretches from Japan through Southeast Asia and across the Pacific basin.

Most are too weak to be felt by humans, but strong and destructive ones come at random with no technology available to predict when and where they will happen.

Raquel Balaba, 58, was with her grandchildren at a primary school in General Santos City when they felt the ground move.

"We were in an open field but the earthquake was so strong that the children got really scared and started crying," Balaba said.

"I got really dizzy so I'm trying to take a rest now. But thank God no one here got hurt."

Some schools in Jose Abad Santos municipality in Davao Occidental province reported cracks in their buildings, said Jason Sioco, a member of the local disaster agency.

But he said there had been no reports of injuries or "substantial damage".

"Power and telephone signals were cut off for a while but electricity is back on," he said.