MANILA, Philippines (AP) — A powerful earthquake with a preliminary magnitude of 7.6 struck Saturday off the southern Philippine coast, prompting many villagers to flee their homes in panic around midnight after Philippine authorities issued a tsunami warning.

The quake struck at at a depth of 32 kilometers (20 miles), according to the U.S. Geological Survey. There were no immediate reports of major damage or casualties.

The Pacific Tsunami Warning Center initially said that based on the magnitude and location, it expected tsunami waves to hit the southern Philippines and parts of Indonesia, Palau and Malaysia. But the center later dropped its tsunami warning.

In Japan, authorities issued evacuation orders in various parts of Okinawa Prefecture, including for the entire coastal area, affecting thousands of people.

Teresito Bacolcol, the head of the Philippine Institute of Volcanology and Seismology, told The Associated Press his agency advised residents along the coast of southern Surigao del Sur and Davao Oriental provinces to immediately evacuate to higher ground or move farther inland.

Owners of boats in harbors, estuaries or shallow coastal waters off the two provinces should secure their boats and move away from the waterfront, the quake agency said in its tsunami warning. Boats already at sea should stay offshore in deep waters until further advised, it said.

Based on the quake's magnitude, Bacolcol said a 1-meter (3.2-foot) tsunami may hit but the wave could be higher in enclosed coves, bays and straits.

Villagers were fleeing their homes to safety around midnight in Hinatuan town and outlying areas in Surigao del Sur province, according to authorities and the government’s disaster-response agency, which said that it could not immediately provide specific details.

Pictures posted on Hinatuan government’s Facebook account show residents fleeing to higher ground on foot or aboard cars, trucks, motorcycles and tricycle taxis at night.

More than three hours after the quake hit, Bacolcol said there was no report of a tsunami hitting the coast from his agency’s field offices but added authorities would continue monitoring.

The Philippines, one of the world's most disaster-prone countries, is often hit by earthquakes and volcanic eruptions due to its location on the Pacific “Ring of Fire,” an arc of seismic faults around the ocean. The archipelago is also lashed by about 20 typhoons and storms each year.