7.9 Earthquake: Philippines struck, tsunami watch in effect

(CNN) -- An earthquake with a preliminary magnitude of 7.9 has struck off the coast of the Philippines, the U.S. Geological Survey said Friday.

The quake prompted a tsunami warning for parts of Indonesia, the Philippines, Taiwan, Japan, Guam and other areas, the Pacific Tsunami Warning Center said.

"An earthquake of this size has the potential to generate a destructive tsunami that can strike coastlines near the epicenter within minutes and more distant coastlines within hours," the tsunami warning center said.

The quake, which was about 20 miles deep, struck just before 8:50 p.m., the agency said.

There were no immediate reports of damage or injuries.