Jakarta, Indonesia ? An earthquake with a magnitude of at least 6.2 struck off the coast of Sumatra on Saturday, triggering a tsunami alert and prompting some residents to flee their homes, officials said.

There were no immediate reports of a tsunami, damages or casualties.

The quake’s epicenter was located off Simeulue island, about 160 miles southwest of Medan, according to the U.S. Geological Survey. It struck just after 9 p.m. local time.

Indonesia’s Meteorology and Geophysics Agency put the quake’s magnitude at 6.2, but the USGS said the magnitude was 6.5. There was no immediate explanation for the discrepancy.