For the third time since February, a mysterious boom was heard and shaking felt Tuesday night by residents across San Diego County.

Are we having an earthquake? Our sliders won’t stop shaking, but my chair isn’t moving and it’s not wind,” a Coronado resident posted to Facebook.

I heard it here on the Strand, but didn’t feel anything. Sounded like 2 loud bangs, I thought it was thunder. I am curious what it could have been,” another Coronado resident posted.

The latest mystery phenomena — sometimes referred to as a skyquake — was reported just before 8:20 p.m. by residents as far south as Tijuana, as far east as El Cajon and in San Diego neighborhoods in the southeast and coastal areas, as well Linda Vista, Clairemont and Tierrasanta.

A similar incident shook the region on Feb. 16. At the time, the United States Geological Survey tweeted that the shaking wasn’t an earthquake “but it may have been a sonic boom which are not too uncommon” in San Diego.

About three weeks later, on March 10, residents across the region again reported a similar shaking and loud boom, though no earthquakes were reported.

On Tuesday night, the USGS website again showed no seismic activity in the region.

While the two previous mystery shaking events occurred within 10 minutes of 5 p.m., Tuesday night’s incident occurred after the sun had set. A few minutes later, San Diego police received several calls regarding the noise and shaking, according to Sgt. Kevin Gibson.