The temblor was also felt at Intensity 4 in the cities of Pagadian and Tacurong and at Intensity 3 in General Santos City, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.
The movement of the Cotabato Trench traversing Central Mindanao and extending beneath the Celebes Sea triggered the quake that registered a magnitude of 5.7 on the Richter scale, it added.
The quake’s epicenter was located at 140 kilometers southwest of Isulan, Sultan Kudarat.
Reports said many of those awake when the quake struck reacted by firing guns in the air and chanting due to a traditional belief that earthquakes can be stopped with loud noises.
Phivolcs director Renato Solidum said aftershocks were expected to follow the tremor.
Seismologist Reiner Amilbahar said that while there was no reported damage, he was worried that "there may be injuries because of stray bullets."
The movement of the Cotabato Trench triggered the magnitude 7.9 earthquake that occurred offshore at 12:11 a.m. of Aug. 17, 1976.
That powerful earthquake beneath the North Celebes Sea spawned the tsunami which destroyed more than 700 kilometers of coastlines bordering the Moro Gulf in the North Celebes Sea and left 4,791 dead, 9,928 injured and 2,288 missing. — Felix de los Santos, Ramil Bajo, Richel Umel, John Unson and wire reports