Perhaps you awoke with a shudder early Tuesday morning at the thought of returning to work following the winter holidays. Perhaps that tremble didn’t come from you at all.

A 2.3 magnitude earthquake registered in Montgomery County early Tuesday. The mild quake originated about 3 kilometers west of Rockville, according to the U.S. Geological Survey. Seismic activity is measured at two locations in Maryland, Soldiers Delight in Baltimore County and Garrett College in western Maryland.

Residents across the region took to social media with anecdotes of feeling the rumble sometime before 1 a.m. Some compared it to thunder or the sound of a garage door opening. Others noticed their family pets seemed agitated.

Earthquakes are rare in Maryland but not unheard of. The state’s strongest confirmed tremor was a 3.1-magnitude event near Hancock, Washington County, in 1978. Such magnitudes are considered minor, and seldom result in significant damage or injury, according to the Maryland Geological Survey.

This story may be updated.