The magnitude 3.7 tremor didn’t cause any significant damage or injuries, but the students were sent to a courtyard while their school was inspected.
Bulgaria’s seismologic center said the quake struck at 7:48 a.m. local time at an epicenter about 6 miles offshore near the village of Kamen Byrag.
It said the earthquake was also felt in some of the nearby villages of the Dobrich District.
The same area was hit by a 5.0 magnitude quake on August 5, which caused cracks to develop in some buildings.