By Gary McWilliams

HOUSTON (Reuters) - The U.S. Coast Guard has suspended the search for a worker missing from an oil production platform in Louisiana's Lake Pontchartrain that exploded and caught fire late on Sunday.

Missing is Timothy Morrison, 44, of Katy, Texas, the Coast Guard said in a statement. Seven other workers were sent to hospital with injuries in the incident.

"The decision to suspend a search is never an easy one," Commander Zac Ford said in the statement.

"We send our thoughts and prayers to the Morrison family and all those affected."

Coast Guard rescue crews battled 4 foot to 5 foot (1.2 meter to 1.5 meter) waves during the search, and a helicopter joined them at daybreak after overnight efforts failed to locate Morrison, officials said at a briefing on Monday.

Three workers remain in hospital for blast and burn treatment, some in critical condition, said Mike Guillot, emergency medical services director at East Jefferson General Hospital, in a news briefing on Monday. Four others were released overnight.

Firefighters managed to turn off a valve that was feeding natural gas to the blaze on the platform, Dave Tibbetts, chief of the East Bank Consolidated Fire Department, said at the same Monday briefing. He said the fire would eventually burn itself out as the gas stopped flowing.

"We feel confident from the firefighters' aspect that we have control of the situation," Tibbetts said.

The platform is operated by Clovelly Oil Co, said Donald Mackenroth, a Clovelly vice president reached by phone.

Details of what happened on the platform are still to be determined, he said on Monday.

There were at least eight people on the platform and a nearby supply vessel at the time of the explosion and fire, officials said. An investigation into the incident is starting, they said.

There was no sign of an oil sheen or other environmental damage on Monday, but officials said they were still evaluating the site. The platform is used to transfer and store oil and natural gas from nearby wells, the officials said.

Police were notified of a loud explosion about 7:18 p.m. on Sunday (0018 GMT on Monday) by residents, and soon after received a call from the platform that a boat carrying injured was on its way to shore, said Lieutenant Brian McGregor of the Kenner, Louisiana, police force.

East Jefferson General Hospital, which received some of the injured, declined to comment on the number of treated or on the type or extent of their injuries.

Clovelly is the only oil company operating in Lake Pontchartrain, according to its former president, Harald Werner. It has two or three active oil and gas wells at the lake, he said.

(Reporting by Apeksha Nair in Bengaluru, India, Peter Szekely in New York, Gary McWilliams in Houston and Brendan O'Brien in Milwaukee; Editing by Jacqueline Wong, Susan Thomas and Tom Hogue)