Residents of central New Jersey were surprised Friday morning by a small earthquake.

The U.S. Geological Survey (USGS) says a magnitude-2.7 quake struck around 3:41 a.m. centered 2 miles north of Bernardsville, NJ.  The quake had a depth of 3.5 miles.

“In the middle of the night we both looked at each other and said what the heck was that?,” resident Danielle Carlson told CBS New York.

“Kind of just like a thunder clap, like a rumble. I woke up because the windows were shaking,” resident Tom Wood added.

The USGS said there was no damage and quake of that magnitude usually does not show damage.  The agency added that quakes usually hit the region every two to three years, although the last quake to strike the area was in December 2014.

One resident said that she knew something was coming because of her dog’s strange behavior.

“The dog was pacing back-and-forth, very neurotic, she’d never been like that before,” Ruth Levin told NJ.com. “She was frightened and stayed next to me all night.”

The USGS admitted there is anecdotal evidence dating back millennia of animals acting in a strange manner hours or weeks before an earthquake.