Booms heard on Sunday evening prompted at least two calls to York County 911, but what caused the noise remains a mystery. The calls came from the southwestern part of the county, York County spokesman Carl Lindquist said. Staff at the 911 center made some calls but were unable to confirm any cause.

Jeri Jones, owner of Jones Geological Services, said he heard two booms at his home in North Codorus Township. The first one around 7:43 p.m. was louder than the second one around 7:52 p.m. It didn’t seem like a seismic event. And it wasn’t an earthquake, Dr. Charles Scharnberger, professor emeritus of the earth sciences department at Millersville University. Nothing showed on the seismograph. READ MORE