Search suspended for missing worker after oil rig explosion in Louisiana Witnesses reported a large explosion, smoke and fire from Lake Pontchartrain.

 -- The search for a missing Louisiana worker was suspended Monday evening after he was unaccounted for following an explosion on a large oil rig Sunday night.

The Kenner Police Department said it fielded a flurry of 911 calls at 7:18 p.m. Sunday after witnesses heard a loud explosion and reported seeing a large fireball and cloud around Lake Pontchartrain, which is just north of New Orleans.

Lt. Brian McGregor told ABC News that after their phone lines lit up, boats were launched by Kenner Police Department and Louisiana Wildlife and Fisheries "within seconds." The crews assisted seven injured workers and transported another four stranded workers aboard the rig to shore, but one victim, identified by the Coast Guard as Timothy Morrison, 44, of Katy, Texas, remained unaccounted for.

“The decision to suspend a search is never an easy one,” said Coast Guard Cmdr. Zac Ford Monday evening. “We send our thoughts and prayers to the Morrison family and all those affected by this incident.”

The majority of victims suffered burn injuries, McGregor said.

Five workers in critical condition were rushed to University Medical Center, a level 1 trauma center, and two others were taken to East Jefferson General Hospital. Michael Guillot, director of East Jefferson Emergency Medical Services, said the victims suffered "blast-type injuries and burns."

Two workers, according to McGregor, who were more stable at the time were transported to Baton Rouge, Louisiana, to receive treatment for fire-related injuries.

Clovelly Oil Company, the owner of the oil rig, released a statement about the fire and its oil and gas production on the platform.

The company said three of the injured were employees and four others were contractors from other companies hired to work on the rig. Morrison, the missing worker, was also a contractor, the statement added.

The blaze has been mostly contained, Jefferson Parish fire officials said at a press conference. The only flame still active on the rig is a shutoff gas light that officials anticipate will burn out on its own.

Initially, officials cautioned that oil could leak into Lake Pontchartrain, but the Jefferson Parish Sheriff's Department and the U.S. Coast Guard stated earlier today that they do not see evidence of environmental issues so far and that no oil sheen has surfaced.

Clovelly stressed that it is working with local authorities to contain the fire and that three oil wells were "shut in" when the blast occurred.

The company said the shut-in took place "shortly after the explosion," but it is unsure whether oil leaked into Lake Pontchartrain.

"Clovelly does not know if any oil was discharged into the lake," the statement read.

At the time of the blast, "routine maintenance was being conducted on the platform," the statement added.

The City of Kenner posted on its Facebook page Sunday evening that "authorities on the scene report that cleaning chemicals ignited on the surface of the oil rig platform."

McGregor said it was too early to confirm the cause of the blast.

"We won't know until you get on the rig to see what kind of maintenance was being done," he said.

The lieutenant, a seasoned veteran, was shocked by the incident.

"I've been here 23 years and this is the first time anything like this happened," McGregor said.

Louisiana State Police is investigating the cause of the explosion.

ABC News' Rachel Katz, Rex Sakamoto and Joshua Hoyos contributed to this report.