Manila: - A strong earthquake hit the southern Philippine island of Mindanao on Sunday, geologists said, causing damage and injuries in an area still recovering from a string of deadly quakes in October.
Police said a rescue operation had been launched at a heavily damaged market building near the 6.8 magnitude quake's epicentre, which is about 90 kilometres (55 miles) from the major city of Davao.
Patients were evacuated from hospitals as a precaution and nervous crowds massed outside shopping malls after the powerful jolt and a series of smaller, but strong aftershocks.
"We can no longer use our office because the walls cracked and the stairs collapsed," local police spokeswoman Lea Orbuda told AFP. "The power is off and the water taps are dry."
She added that at least 24 people had been taken to the hospital, but was not aware of any reports of deaths as search operations continued.
President Rodrigo Duterte, who is from Davao, was caught up in the earthquake but was unharmed, officials said.
"The First Lady... said the car she was riding (in) was swaying," spokesman Salvador Panelo said. "They are unhurt."
There was no threat of a tsunami, said the US Geological Survey, which initially reported the magnitude at 6.9.
The Philippines is situated on the Pacific "Ring of Fire", an arc of intense seismic activity that stretches from Japan through Southeast Asia and across the Pacific basin.
Three quakes above 6.0 magnitude hit roughly the same area of Mindanao in a matter of weeks in October, killing some two dozen people and heavily damaging office buildings, schools and apartments.
Tens of thousands of people were forced into shelters by the string of tremors, the government said, either because their homes were damaged or they were too afraid to return.
Most of the deaths in October were due to collapsing walls and falling debris, including a teenage boy who was crushed by a falling wall as he tried to escape his school.
Other fatalities were attributed to rock and landslides unleashed by the violent shaking that injured at least 400 people.
The Philippines has been hit by several very powerful earthquakes in recent decades, including one of magnitude 7.8 that struck the northern resort town of Baguio in 1990.
That tremor toppled multi-story buildings and hotels, killing some 1,200 people.