"It amounted to an extremely loud noise," ETSU Public Safety Director Jack Cotrel said of the explosion, which occurred shortly after midnight on the sand volleyball court near the Davis Apartments complex.
Cotrel said investigators determined that the bomb was a homemade device constructed from bottle rockets. It was detonated on the surface of the sand, leaving a depression about the size of a shallow punch bowl.
The explosion was loud enough to create a commotion on campus, waking students in nearby residence halls.
No arrests were made. Cotrel said the investigation was ongoing, and investigators were interviewing people on campus regarding the explosion.
The university received assistance from the Bureau of Alcohol, Tobacco and Firearms and the State Fire Marshal's Office, Cotrel said.