DAVAO • An earthquake of magnitude 6.6 sent people scrambling yesterday as it shook buildings and disrupted power supply in the central area of the Philippines' southern island of Mindanao, killing at least two and injuring dozens, the authorities said.

The quake, which struck at 9.04am, opened cracks in buildings and showered debris on a 66-year-old man and a 15-year-old student, killing them, police and disaster officials said.

"The earthquake was very strong," Ms Abi Agduma, a shopkeeper on the island, told broadcaster DZMM radio.

"We ran outside our home. I looked at our store and our house, and they looked like they were dancing.

"My knees are still shaking," she added.

Power cables swayed in Davao city, the home town of Philippine President Rodrigo Duterte, where people rushed to open spaces, while some fainted out of fear. The quake also triggered power cuts in nearby General Santos city, the media said.

"Inspection is ongoing and the disaster-risk office is checking our roads and bridges," said Mayor Sara Duterte of Davao city. She is the daughter of President Duterte, who was himself the city's mayor for many years.

Some schools in the area have also suspended classes.

Disaster officials said they were monitoring the situation, as further information on damage and possible casualties trickles in.

Earthquakes are common in the Philippines, which is on the geologically active Pacific Ring of Fire.

The quake, whose magnitude was initially put at 6.7 by the European-Mediterranean Seismological Centre, was the second powerful quake to strike Mindanao in two weeks.

A quake of magnitude 6.3 on Oct 16 killed seven and injured more than 200, the Philippine disaster agency said.