Coast Guard officials said an oil rig exploded in the Gulf of Mexico off the coast of Louisiana, sending four people to area hospitals on Friday, while two others were believed to be missing and another two were determined dead, the BBC reported.

Three of the four people taken to area hospitals were said to be in critical condition, according to WVUE's Chris Finch.

The oil rig is a production platform owned by Black Elk Energy and is located about 25 miles southeast of Grand Isle, La.

Coast Guard Capt. Peter Gautier explained to WWL TV that 28 people were thought to be aboard the rig at the time.

Since the explosion, 20 people were evacuated to nearby rigs and oil platforms, seaman Drake Foret, told the BBC.

The platform was not actively producing oil, so it’s unlikely the incident will cause a major environmental disaster, Gautier explained to the Associated Press.

As of now, its unclear if oil has spilled into the water.

Maintenance workers were cutting into a pipe and oil may have escaped causing the explosion on Friday morning, some reports said.

The Associated Press reported that two helicopters, an airplane and small boats were sent to the area, and the fire has since been put out as of 10.30 a.m.

The Black Elf Energy platform is a production platform, unlike the Deepwater Horizon rig that was drilling a mile-deep water well for oil giant BP, east of where Friday’s explosion was reported.

A spokesperson for Black Elk, an independent oil and gas company based in Houston, has yet to comment on the recent explosion in the Gulf of Mexico.

The explosion occurred just one day after U.S. Attorney General Eric Holder said oil major BP would have to pay a record criminal fine of $4.5 billion (£2.8bn) dating back to the 2010 Deepwater Horizon disaster.