A crew worker who went missing after an oil and gas platform explosion in Lake Pontchartrain late Sunday night has been identified as 44-year-old Timothy Morrison, of Katy, Texas. 

Jefferson Parish Sheriff Joseph Lopinto identified Morrison as the missing crew member at a 4 p.m. news conference Monday. 

Lopinto said the search for Morrison is ongoing, with Coast Guard and Jefferson Parish Sheriff's Office helicopters and boats in use.

A crew boarded the rig to attempt to find him, but was unable to due to structural damage in certain areas. Lopinto said the crew will return to the rig Tuesday with equipment to clear debris and continue the search. 

Lopinto said Morrison's wife and family have been notified of his missing status. 

The explosion sent seven people to the hospital. As of Monday morning, three remain, and four have been discharged.

The JPSO identified the injured crew members as Alvin Kembrel, 55, of Belle Chasse,  Lawrence Dufrene, 45, of Marrero,  James Bordelon, 62, of Laplace, Devin Billiot, 27, of Houma, Brent Neil, 52, of Houma, Paul Phister, 52, of Mandeville, and Cody Boudreaux, 23, of Chavin.

A news release said Bordelon was taken to University Hospital and is recovering from surgery.

Dufrene and Kembrel were also sent to University Hospital initially, but later sent to Baton Rouge General Hospital's burn unit due to the severity of their injuries.

Billiot, Neil, Phister and Boudreaux have all been treated and released. 

While there was also a crew boat out near the rig at the time of the explosion, it was not immediately clear whether some of those injured had been on the crew boat or if they were all from the rig. 

Hydra Steam Generator, Inc., a Houston, Texas subcontractor working on the platform, was hired to perform a cleaning measure on the platform's pipe, the JPSO said. At some point during the process, an explosion occurred which resulted in a large fire at the top tier of the platform, owned by Clovelly Oil Company LLC of New Orleans.

The cause for the explosion is unknown and being investigated.