Wreckage smolders after an explosion at the Jay paper mill Wednesday. The explosion shook the ground and produced a plume of black smoke that was visible for miles. Russ Dillingham/Sun Journal

JAY — The State Fire Marshal’s Office said Friday that more work remains before its investigation into a Wednesday afternoon explosion at the Androscoggin Mill is finished.

Investigators said several mill workers who were in the vicinity of the blast were able to shut valves, preventing further damage in the mill digester.

Fire investigators finished their on-site work at the mill Friday afternoon, according to Maine Department of Public Safety Spokesman Stephen McCausland. A team of boiler and pressure vessel inspectors from the Maine Department of Professional and Financial Regulation, who joined the investigation, have additional work to complete.

Fire investigators, assisted by Jay Police, interviewed several mill employees who were in the immediate vicinity of the digester when it exploded.

None of those workers was injured in the blast.