A 6.1-magnitude earthquake struck off the coast of Sumatra, Indonesia, making it the third tremor to shake the region since early Monday, according to the nation’s geophysics agency.

Just before 10.30 a.m., a shallow earthquake off the Mentawai islands, off the west coast of Sumatra, was detected by Indonesia’s meteorological and geophysics agency (BMKG), although no tsunami warning was issued.

The agency had earlier recorded a magnitude of 6.4 but revised that to 6.1, a BMKG spokesperson said.

Three consecutive earthquakes struck the area with increasing intensity since the early hours of Monday, with a 5.2-magnitude tremor recorded before dawn, followed by a 5.4-magnitude quake less than an hour later.

The 6.1-magnitude earthquake was felt strongly for several seconds by residents in the Mentawai islands, in the provincial capital of Padang, and in the surrounding mountainous area of Bukitinggi, the disaster agency said in a statement.

The agency said there were no reports of casualties but there was minor damage to buildings on Siberut island.

Separately, Novriadi, a local disaster official in the Mentawai islands, told Reuters that residents in several villages had been evacuated to higher ground and a local church, school and health facility had been slightly damaged.

The disaster agency urged the public not to panic and warned of the potential for aftershocks.

Padang was struck by a 7.6-magnitude earthquake in 2009 that killed more than 1,100 people, injured many more and caused widespread destruction.

Indonesia straddles the so-called “Pacific Ring of Fire”, where different tectonic plates of the Earth’s crust meet and create frequent seismic activity.