MASON CITY, Iowa — An explosion Tuesday at Soy Energy in Mason City remains under investigation today.

The Mason City Fire Department responded to a call of an explosion at 4172 19th St. S.W., Mason City, just before 6 p.m. Tuesday.

Firetrucks and firefighters could be seen on the west side of the plant, but no damage or smoke was visible from the outside. An alarm could be heard sounding.

No one appeared to be injured and employees were gathered outside of the front office building.

Soy Energy produces soybean oil-based biodiesel and corn stillage oil-based biodiesel.

The Mason City Fire Department was expected to release more information later today.

Soy Energy also declined to comment until later today.

— Mason City Globe Gazette