MANILA, Philippines — A 7.6 magnitude earthquake off the coast of the Philippines has prompted a tsunami alert, warnings of structural damage and an urgent call for people to move to higher ground.

“People in threatened coastal areas are strongly advised to immediately evacuate,” the Philippine Institute of Volcanology and Seismology said late Friday.

“Boats at sea are advised to stay in the deeper parts of the open seas until the threat has passed. If there is sufficient time, boats in harbors and enclosed bays are advised to go to the deeper parts of the open seas until the threat has passed.”

The quake, which was about 20 miles deep, struck just before 8:50 p.m., authorities said. Its center was about 65 miles southeast of the coastal town of Guiuan, in the Philippine province of Eastern Samar.

The quake prompted a tsunami warning for parts of the Philippines and Indonesia, the Pacific Tsunami Warning Center said. The U.S. Geological Survey initially said the quake had a magnitude of 7.9 but later revised that figure.

A tsunami watch was in effect for the Marshall Islands, Wake Island, Solomon Islands, several other Pacific islands and parts of Russia, the center said. Authorities did not immediately know whether the earthquake actually had generated a tsunami.

“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 Philippines coastal areas of Northern Smar, Eastern Samar, Leyte, Southern Leyte, Surigao del Norte, and Surigao del Sur fall under the tsunami alert.

Aimee Menguilla, information officer of Philippines’ National Disaster Risk Reduction and Management Council, said the agency has advised regional authorities to alert citizens about possible tsunami waves.

“This is not new to us,” she said. “We do regular tsunami exercises.” But people need to be “particularly alert” because the earthquake occurred at night.

She said the quake was centered in the Marianas Trench in the western Pacific Ocean and was felt in the country’s east. There have been no reports, she said, of damage or injuries.

Paul Daza, governor of Northern Samar, said officials are informing citizens of evacuation and “everyone is cooperating.”

“Most of our towns are at risk of the possible tsunami,” he said. “There are emergency plans if needed, but hopefully there will be no tsunami.”

Marie Elairon, working at the front desk at Hotel Dona Vicenta in Borongan, Eastern Samar, said some people are headed to mountainous areas and others have taken shelter in a church.

“There is no panic right now,” she said, “but we are being safe and still evacuating.”

Dan Molina, a hotel employee in Guiuan, said, “We are advised to go up,” referring to higher ground.

Ed Serrano, the head of security at the Marco Polo Hotel in the city of Davao, about 250 miles south of Guiuan, said he felt the ground shake.

“The quake was very strong and the hotel guests were panicking. Most of them went outside,” he said. “But now, the situation is under control and we are waiting for official reports on how strong the quake was.”

Witnesses in the east said they were seeing four-foot waves.

An initial tsunami warning issued for Japan, Taiwan and several Pacific islands was lifted.

— CNN’s Zarifmo Aslamshoyeva, Aliza Kassim, Ben Brumfield, Mariano Castillo and Joe Sterling in Atlanta and Journalist Maria Ressa in Manila contributed to this report.