Jakarta -- A magnitude 6.8 earthquake struck just off the coast of southern Sumatra, Indonesia, on Saturday evening, the U.S. Geological Survey reported.

No agencies reported any damage or injuries, and a tsunami was not expected.

The Pacific Tsunami Warning Center said a "destructive widespread tsunami threat does not exist based on historical earthquake and tsunami data.

"However, there is a very small possibility of a local tsunami that could affect coasts located usually no more than 100 kilometers from the earthquake epicenter," the tsunami warning center said in a statement.

The quake happened about 11 p.m., the USGS said. It was centered about 147 kilometers (91 miles) west-southwest of Bengkulu, Sumatra, and 671 kilometers (417 miles) from the Indonesian capital of Jakarta.

The National Meteorology and Geophysics Agency in Jakarta said it measured the first quake at 6.7 and a second quake, at 11:47 p.m., at 6.3.

The USGS shows a second quake, a magnitude 5.7 at 11:11 p.m., but not a later quake.

The quake was not felt strongly in Padang, Sumatra, 367 kilometers (228 miles) south of the epicenter, according to the local disaster agency, which said it had received no reports of damage or injuries.

In Bengkulu, Sumatra, people ran out of their homes and gathered in open spaces when the quake hit, according to Supriyanto of the Bengkulu military district command, who like many Indonesians only uses one name.

Although people were returning later Saturday night, many residents said they were staying up for fear of aftershocks, he said.

The National Meteorology and Geophysics agency also said it had received no reports of damage or injuries. No tsunami alert was issued because the quakes were below a magnitude 7.0, officials said.

The earthquake's epicenter was 4.7 kilometers (2.9 miles) below the Earth's surface, according to the USGS. In general, earthquakes centered closer to the Earth's surface produce stronger shaking and can cause more damage than those farther underground.