The blast at the Williams Olefins facility in Gaismar killed one person.
Ambulances and helicopters took thirty other workers to area hospitals with various injuries, including burns.
One person is in critical condition. Two others are in serious condition.
Plant officials say as many as 600 people were working there at the time of the explosion.
Olefins is a petro-chemical that includes ethylene and propylene. The Williams website says the Gaismar facility produces about 1.3 billion pounds of ethylene a year, and another 90 million pounds of polymer-grade propylene.
The explosion occurred at 8:37 a.m. By 1p.m., emergency crews had put out the fire and hazardous materials crews had things under control.
Now comes the hard part.
For the operators, figuring out what happened.
For the survivors, figuring out why.