Tampa Electric Co. and Gaffin Industrial Services Inc. have been cited after five employees were killed, and one other suffered serious burns, in an accident last June. 

The U.S. Department of Labor's Occupational Safety and Health Administration made the announcement Friday.

Workers at the TECO Big Bend power plant were trying to unplug a blocked tank in June when molten material poured onto them.

Inspectors determined that the employees were burned when a blockage inside a coal-fired furnace broke free and spewed molten slag into the work area.

OSHA cited Tampa Electric for failing to follow energy control procedures while performing maintenance on equipment.

Gaffin Industrial Services was cited for failing to develop procedures to control hazardous energy.

Tampa Electric and Gaffin were also cited for failing to provide appropriate personal protective equipment to safeguard employees from burns. Proposed penalties for both companies totaled $160,972.

"This tragedy demonstrates what can happen when hazards are not properly controlled," said OSHA Atlanta Regional Administrator Kurt Petermeyer. "Employers must develop and implement necessary procedures to prevent incidents such as this from occurring."

The companies have 15 business days from receipt of their citations and proposed penalties to comply, request an informal conference with OSHA’s area director, or contest the findings before the independent Occupational Safety and Health Review Commission.