Three people were injured, one seriously, in an explosion Wednesday afternoon at Northeast Agricultural Sales Inc. at 26 North Road in Detroit.

Pittsfield Fire Chief Bernie Williams said the explosion was caused when a spark in a hopper ignited sulfur dust that exploded. He said fire officials were still working to find what the exact cause of the spark was.

Of the three injured, Williams said one man was transported by LifeFlight to Portland with burn injuries. The other two were taken to the Sebasticook Valley Hospital in Pittsfield with lesser injuries. Their identities were unavailable.

There was no visible sign of damage and everything at the scene seemed to be still intact, Williams said, and the fire was contained to a bin-like container where products are mixed before being dropped into trucks.

The explosion occurred in back of the company’s building, and media were unable to access that area.

Emergency officials responded to the report of an explosion just before 2 p.m. Wednesday. A dispatcher at Somerset County Communications Center in Skowhegan said at 1:50 p.m. that fire units were at the scene. A woman who answered the phone at the business just after 2 p.m. said the explosion happened between 1 p.m. and 1:30 p.m.

Steve McCausland, spokesman for the state Department of Public Safety, said in an email at 2:17 p.m. that investigators from the Office of Maine state Fire Marshal were en route to the scene.

Responding to the scene were Detroit, Pittsfield, Newport, Corinna and Skowhegan firefighters, Somerset County Sheriff’s officers, state police, Plymouth Rescue, Sebasticook Valley Health ambulance and state Department of Environmental Protection officials.

Northeast Agricultural Sales, which sells farm equipment, is off Route 100 in Detroit, a small town in Somerset County.

Staff writer Colin Ellis contributed to this report.

Amy Calder — 861-9247

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Twitter: @AmyCalder17