An offshore oil rig in the Gulf of Mexico exploded Friday morning, killing two and injuring several others.

The U.S. Coast Guard told Louisiana's that the rig, run by Houston-based Black Elk Energy, was not producing oil when the blast hit, averting the potential for environmental catastrophe.

The company said that the fire was out shortly after 11 a.m. central, according to Reuters. Four people had to be airlifted to a hospital in nearby Grand Isle, Louisiana, and were said to be in critical condition. Another two were still missing.

It wasn't immediately clear what caused the blast or the resulting fire. noted that Black Elk Energy has 854 wells on 155 different offshore drilling platforms, mostly clustered between Corpus Christi, Texas and the mouth of the Mississippi. The station added that Black Elk CEO John Hoffman spent 18 years working for the energy company known today as BP.

BP agreed on Thursday to pay a total of $4.5 billion for the company's 2010 Gulf of Mexico oil spill, a disaster that was ongoing for months after an explosion on an offshore drilling rig killed 11 workers.


Photo: U.S. Department of Energy.