Three men in Detroit were taken to the hospital Wednesday after an explosion in an 86-foot-tall silo used to store sulfur.

All three men work for Northeast Agricultural Sales.

Anthony Towers, 62, of Newport was taken by Lifeflight helicopter to Maine Medical Center in Portland with extensive burns, according to a Thursday news release from the Maine Department of Public Safety.

Lee Gustin, 50, of Cambridge and Clarence Rider, 36, of Pittsfield both complained of respiratory issues and were taken to Sabasticook Hospital in Pittsfield.

Both Towers and Rider were on top of the silo when the explosion occurred. Towers was using a shovel to clean out accumulations of dust and sulfur when a spark set off the explosion, setting Towers' clothing on fire.

Investigators are still working to determine what caused the spark.