The Coast Guard kept searching by air and sea for 12 people missing off the coast of Louisiana on Wednesday, hours after six other crew members were pulled from rough seas following the capsizing of their commercial platform vessel during a “microburst” of bad weather.

The search involved at least four Coast Guard vessels, four private ones and Coast Guard airplanes based in Corpus Christi, Texas, and Mobile, Alabama. A Coast Guard helicopter also was being used.

Lafourche Parish President Archie Chaisson III confirmed that 18 people were on board before the Seacor Power flipped over in rough seas.

“The hope is that we can bring the other 12 home alive,” Chaisson said Wednesday morning. Time is of the essence in the rescue efforts, as “we have the potential for some rough weather around lunchtime,” he added.

Relatives of the missing crew members rushed to the port from their homes nearby, seeking any information they could get, Chaisson said.

“We continue to pray for the 18 men who were on that vessel as well as their families,” Chaisson said.

The company involved, Houston-based Seacor Marine, set up a private hotline to share information with families of those onboard, Chaisson said. An employee who answered the phone Wednesday morning said he had no immediate information he could share.

The National Weather Service in New Orleans had been warning of bad weather offshore, including a special marine warning issued before 4 p.m. Tuesday that predicted steep waves and winds greater than 50 knots (58 mph).

The Seacor Power crew, sent an emergency distress signal a half-hour later, at 4:30 p.m., according to the Coast Guard, which then issued an urgent marine broadcast that prompted multiple private vessels in the area to respond, saving four of the crewmembers, the agency said. Coast Guard crews in boats rescued another two people. A search plane also joined the effort, miles south of Port Fourchon.

“There was a microburst of weather that came through the area at the time,” Coast Guard Petty Officer 2nd Class Jonathan Lally said.

The Seacor Power, a bulky vessel 129-feet (39-meters) long at its beam, is designed to become an offshore platform by dropping three towering legs down to the sea floor. It flipped over in the high wind and rough seas. At one point, it would be seen on video with one of its legs pointed awkwardly skyward as rescuers searched in the heaving water.

Port Fourchon, Louisiana’s southernmost seaport, is a major base for the U.S. oil and gas industry, supporting most of Louisiana’s offshore platforms and drilling rigs.

The storm also overturned other vessels and damaged property from Louisiana’s shore up to New Orleans. The Coast Guard warned in a Facebook post that the storms caused “significant hazards to life and property.”

“Please join @FirstLadyOfLA and me in praying for those who remain missing after yesterday’s capsizing off the coast of Grand Isle and for those who are working to rescue them,” Louisiana Gov. John Bel Edwards said on Twitter Wednesday morning.