MANILA, Oct. 10 (Xinhua) -- Philippine President Ferdinand Romualdez Marcos has directed government agencies to immediately evacuate people in the coastal areas threatened by a tsunami after a powerful earthquake struck off the coast of Davao Oriental province in the southern Philippines on Friday morning.

In a statement, Marcos urged people to "stay alert and calm," and "move to higher ground and stay away from the shore until authorities declare it safe."

"I have directed the National Disaster Risk Reduction and Management Council, the Office of Civil Defense, the Armed Forces, the Philippine Coast Guard, and all concerned agencies to immediately carry out evacuations in coastal areas, activate emergency communication lines, and coordinate closely with local governments," he said.

The president said search, rescue, and relief operations are already being prepared and "will be deployed as soon as it is safe to do so."

The Philippine Institute of Volcanology and Seismology has downgraded the offshore earthquake from a magnitude 7.6 to 7.4.

In an updated bulletin, the institute said that the quake, which occurred at 9:43 a.m. local time (0143 GMT), struck at a depth of 23 kilometers, approximately 43 kilometers northeast of the municipality of Manay.

The institute also issued a tsunami warning in the coastal areas in Mindanao and at least three central Philippine provinces.

"These waves may continue for hours," the warning said, urging residents in the coastal areas to immediately evacuate to higher ground or move farther inland.

Many netizens shared their feelings and experiences of the earthquake on social media. Images showed part of a shopping mall that collapsed in Butuan City, Agusan del Norte, with debris crashing onto several parked cars.

The Davao International Airport sustained damage from the earthquake, according to local reports.

Local media have reported two deaths: a man from Mati City in Davao Oriental province who was reportedly crushed by a fallen wall in his house, and another buried in a landslide in Pantukan town in Davao de Oro province.