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

There were 3-centimeter-high waves at Legaspi in the eastern Philippines, but warnings for the Philippines and Indonesia and watches for other regions were later canceled, the Pacific Tsunami Warning Center said.

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.

Earlier, the Philippine Institute of Volcanology and Seismology had issued an alert strongly advising people in the eastern coastal stretches to "immediately evacuate."

Boats at sea were "advised to stay in the deeper parts of the open seas until the threat has passed." Boats in harbors and enclosed bays were advised "to go to the deeper parts of the open seas until the threat has passed," the alert said.

The Philippines coastal areas of Northern Samar, Eastern Samar, Leyte, Southern Leyte, Surigao del Norte and Surigao del Surfell fell under the tsunami alert.

The tsunami warning center said the quake had "the potential to generate a destructive tsunami that can strike coastlines near the epicenter within minutes and more distant coastlines within hours."

Authorities in the Philippines geared up to warn citizens about tsunami waves.

"This is not new to us," said Aimee Menguilla, information officer of the Philippines' National Disaster Risk Reduction and Management Council. "We do regular tsunami exercises."

Citizens needed to be "particularly alert" because the earthquake occurred at night. That's because people at home and in bed during a tsunami could be sitting ducks.

She said the quake was centered in the Marianas Trench in the western Pacific Ocean and was felt in the country's east.

Paul Daza, governor of Northern Samar, said officials told citizens about an evacuation, and everyone cooperated.

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

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

Paul Earle, a U.S. Geological Survey seismologist, said the quake was "fairly far off the coast, so it likely won't cause severe shaking damage." But, he said, an earthquake "this large could cause a lot of damage" if it were inland.

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 saw 4-foot waves.

The U.S. Geological Survey initially said the quake had a magnitude of 7.9 but later revised that figure. An initial tsunami warning issued for Japan, Taiwan and several Pacific islands was lifted.

A tsunami watch had been in effect for the Marshall Islands, Wake Island, Solomon Islands, several other Pacific islands and parts of Russia, the center said.

CNN'a Zarifmo Aslamshoyeva, Aliza Kassim, Ben Brumfield, Mariano Castillo and Joe Sterling reported from Atlanta, and journalist Maria Ressa reported from Manila.