A malfunction in an electrical panel caused a transformer to explode at Pioneer Hydropower in Ware, Mass. Three workers were injured in the electrical accident last week. 

According to a report from Mass Live, a malfunction in an electrical panel caused it to arc. The malfunction also caused a power overload in an outside transformer, setting off a small brush fire. The three employees were alone in the plant when the panel arced.

One worker is still being treated for severe burns at a facility in Boston, while the other is receiving treatment at the University of Massachusetts Medical Center in Worcester. The workers were doing work on high voltage wiring, according to the State Fire Marshal's office.

The Massachusetts Department of Environmental Protection was also called to investigate because the transformer which overheated is an older one and contains oil and potentially hazardous PCBs