A strong earthquake rocked parts of Indonesia's Sumatra island early Saturday, causing some people to flee their homes, but there were no reports of damage and no tsunami was triggered.

The magnitude 6.1 quake struck at 3:54 a.m. and was centered under the Indian Ocean 175 miles northwest of Sumatra, the U.S. Geological Survey said.

"It felt pretty strong," state news agency Antara quoted one villager as saying. "The whole family and our neighbors ran out from our house, but there was not a massive panic."

Officials on Sumatra were not available for comment early Saturday. There were no immediate reports of damage.

Sumatra was hardest hit by a powerful December 2004 earthquake and tsunami. More than 216,000 people in Indian Ocean nations were killed or missing in the disaster.

The region is rocked by many earthquakes, including a magnitude 8.7 quake in March last year that killed about 900 people on an outlying island.