The U.S. Justice Department said it filed criminal charges in response to a 2012 oil platform incident in the Gulf of Mexico that left three workers dead.

Three rig workers were killed following an explosion on a rig in the Gulf of Mexico operated by Black Elk Energy. The company said a third-party investigation found contractors on the rig failed to follow basic safety standards during construction work.

The U.S. Interior Department described the incident as one of the worst in terms of the loss of life since the Deepwater Horizon tragedy in 2010. Three individuals and companies Black Elk, Grand Isle Shipyard and oil field services company Wood Group now face charges from the Justice Department ranging from manslaughter to violations of the federal Clean Water Act.

"Workers lives can depend on their employer's faithfulness to the law, not least of all those working in oil and gas production where safety must be a paramount concern," John C. Cruden, an assistant attorney general in the Justice Department's environmental division, said in a statement. "The Justice Department is committed to enforcing the nation's bedrock environmental laws that protect the environment, and the health and safety of all Americans."

Investigators said rig workers cut into a pipeline on the platform that had oil inside, starting a fire. The Justice Department said safety procedures governing that type of work were not followed on the rig at the time of the incident.

The U.S. Interior Department's Bureau of Safety and Environmental Enforcement said in late 2013 that Black Elk lapsed on several safety requirements on the rig and operated "a climate in which workers feared retaliation if they raised safety concerns." Black Elk said it disagreed with those findings.

There was no public statement issued in response to the charges filed by the Justice Department.