A Florida power company has been fined $500,000 by a federal judge for violating a federal safety rule and causing an explosion at a coal-fired power plant that killed five people.

The Occupational Safety and Health Administration rule that required workers to receive a pre-job briefing about the work they were to perform was violated by the company. Five employees died as a result of failing to hold the briefings.

As part of the sentence, the United States District Court for the Middle District of Florida ordered the electric company to have a safety compliance plan in place.

According to the plea agreement, the families of each person killed in the blast and several others harmed by it were given confidential settlements by the electric company.

Todd Kim, an assistant attorney general with the Justice Department's Environment and Natural Resources Division, said in a statement on Friday that the willful violation had catastrophic consequences.

Archie Collins, the company's president and chief executive, released a statement after officials from the company were not available for an interview.

Our commitment to hold ourselves accountable for this tragedy and to ensure our people are safe as part of the world-class safety culture is something we are working together to build.

On June 29, 2017, one of the tanks on a coal-fired furnace at the Big Bend Power Station in Apollo Beach, Fla., was blocked by a glass-like waste product formed after the remains of burnedcoal are mixed with cold water.

The written procedure for this work could not be found, so the contractor was called in to perform a water-blasting technique to clear the slag.

The blast sprayed the workers with molten slag, which can reach temperatures over 1000 degrees. One witness described the blast as a volcano and a jet dragster, prosecutors said. A fireball was coming out.

According to court records, O.S.H.A. investigators found that one of the operators had never seen the company's procedure on water-blasting tanks.

According to prosecutors, holding a pre- job briefing would have helped the company stop the work and shut down the unit because it was dealing with an uncommon obstruction.