Firemen try to put out a fire inside a mall following a 6.4-magnitude quake in General Santos City in Mindanao. Edwin Espejo/ AFP

A 6.4-magnitude earthquake has been felt on the Philippines second largest island. Three children were among four people killed in this powerful quake on Thursday.

The quake struck the Mindanao region, which makes up the southern third of the Philippines, on Wednesday night.

On Thursday morning, local authorities confirmed four people had been killed but said the death toll was not expected to rise significantly with no casualties reported in Mindanao's major cities.

The Philippines is part of the Pacific “Ring of Fire,” an arc of intense seismic activity that stretches from Japan through Southeast Asia and across the Pacific basin.

Two people were killed and 18 injured in a landslide in Magsaysay town in Davao del Sur province, national disaster agency spokesman Mark Timbal said.

Patients and residents rest outside a hospital in Makilala town, North Cotabato province in southern island of Mindanao.

A seven-year-old girl was killed when a wall in her house collapsed, said Reuel Limbungan, mayor of Tulunan town in North Cotabato province.

The disaster agency said 27 people were injured and 15 buildings damaged, including shopping malls, schools and town halls.

The earthquake also shook Davao City, the home town of President Rodrigo Duterte and among the most populous cities in the country.

Debris is scattered on the floor of a damaged building in Digos, Davao del Sur province, southern Philippines on Wednesday.

The quake struck 69 km (43 miles) north-northwest of the city of General Santos, Mindanao at 7:37pm (1137 GMT), the United States Geological Survey said. The epicentre was about 80 km southwest of central Davao.

“We felt a very strong jolt and there was a blackout. I saw people rushing down. We were panicking, heading to the exit,” said Naru Guarda Cabaddu, a hotel consultant visiting Kidapawan City between the epicentre of the quake and Davao.

51 injured as quake rocks southern Philippines

The Philippines is on the geologically active Pacific Ring of Fire and experiences frequent earthquakes.

“I was driving back home when I felt a very powerful shake. I stopped and saw people and patients running out of the hospital,” Raprap Rafael, a resident of Kidapawan City, told Reuters.

A community at the foot of a mountain had to evacuate because of more than 200 aftershocks, Psalmer Bernalte, a Kidapawan city disaster official, told CNN Philippines channel.