— Federal investigators are expected in south Louisiana at the site of an explosion that killed one worker at a chemical plant in Donaldsonville, the second such blast in the area in as many days.

State Police Trooper Jared Sandifer said Saturday that officials from the Occupational Safety and Health Administration would visit the CF Industries facility as soon as the site was safe. Sandifer said the state police’s hazardous materials unit was at the plant overnight.

“Once they deem it safe, they will pull out and let OSHA and company officials do their work,” Sandifer said.

Police said Ronald “Rocky” Morris Jr., 55, of Belle Rose, La., was killed in the blast Friday. He had worked at the plant for 34 years, company officials said.

CF Industries identified its injured employees as Courtney Julien, Melvin Singleton, Jeramy Worsham and Kade Yarbrough. Three contractor employees also were hurt.

The company said in a statement Saturday that one of its employees remained hospitalized in stable condition and that all the other workers were released from Baton Rouge-area hospitals.

CF Industries manufactures ammonia and other nitrogen fertilizers at the Donaldsonville facility. Officials said there were no hazardous materials at the site.

The company said that the blast occurred about 6 p.m. Friday in a section of the plant that had been shut down for maintenance and that there was no fire, chemical release or threat to the community.

Lou Frey, vice president and general manager of the Donaldsonville Nitrogen Complex, said the incident involved a rupture in a small vessel or “header” as nitrogen was being offloaded from a tank truck. CF officials said everything was secure at the plant.

“Our focus is on our number one priority — the health and safety of our employees and the community,” Frey said in a statement. “We are deeply saddened by the loss of one of our employees.”

At a Friday night news conference at the plant site, Louisiana State Police Superintendent Col. Mike Edmonson described the incident as a “catastrophic failure” of a manifold that is used to distribute gas to the facility. He said authorities are investigating whether it was a result of over-pressurization or something else.

“We don’t know if it was mechanical; we don’t know if it was caused by over-pressurization. We’ll find that out as we work with plant and as we talk to the personnel,” Edmondson said.

CF Industries’ Web site says the plant can produce roughly 5 million tons of nitrogen for agricultural and industrial uses annually.

Just miles away Thursday, two people were killed and dozens were injured in an explosion at a chemical plant in Geismar owned by Williams Cos. Donaldsonville and Geismar are both in Ascension Parish and straddle the Mississippi River between New Orleans and Baton Rouge.

Friday’s deadly blast wasn’t the first at the company’s Donaldsonville plant. Three workers were killed and nine injured by an explosion and fire at the facility in May 2000.

Later that year, OSHA imposed a fine of nearly $150,000 against CF Industries, citing the company for 14 safety and health violations, 12 of which were described by the agency as serious. The company didn’t contest the citations and agreed to pay the penalties.