Story highlights The plant manager says he doesn't think the injuries are life-threatening

The sheriff explains the deadly incident "was kind of like a balloon popping"

The plant manager says it's still not known what happened

The explosion comes a day after a chemical plant blast in the area killed 2

One person died and eight others were injured in a blast Friday evening at a chemical plant in Donaldsonville, Louisiana, police said.

The incident occurred at a CF Industries facility in the Mississippi River community of about 7,500 people, located some 40 miles south of Baton Rouge. According to its website, CF Industries is "the second largest nitrogen fertilizer producer in the world and the third largest phosphate fertilizer producer among public companies."

Nitrogen was being offloaded from a tanker truck inside the Donaldsonville plant when "a small vessel ruptured," plant manager Louis Frey said.

"We don't know exactly what happened," he said.

Frey insisted "there was no explosion and no fire. It ruptured." Ascension Parish Sheriff Jeffrey Wiley explained, "It was kind of like a balloon popping."

Two of the eight people injured were airlifted from the plant, and Frey said it was his understanding none of the injuries are considered life-threatening. Louisiana State Police Lt. John Cannon had told CNN that two people were critically injured in the incident.

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The parish sheriff stressed that there was never any danger to the general public from the blast or any dispersal of chemicals.

"This was an isolated incident that was ... immediately contained," Wiley said. "There was never a threat of... off-site impact."

The blast comes a day after two people died and more than 100 others were injured in an explosion at another at Louisiana chemical plant -- that one in Geismar, which is about 10 miles north of Donaldsonville and also in Ascension Parish.

Authorities didn't know immediately what caused that explosion at the Williams plant, which produces about 1.3 billion pounds of ethylene and 90 million pounds of polymer-grade propylene each year, according to the company's website.

In addition to 29-year-old Zachary Green's death, dozens were hospitalized for burns, cardiac issues and blunt trauma, Louisiana Department of Health spokeswoman Christina Stephens said.

The U.S. Chemical Board -- the independent federal agency that probes industrial chemical incidents -- announced Friday that one of its investigative teams was heading to Geismar.

Both explosions happened two months after 15 died following a fire and twin blasts at a fertilizer plant facility that decimated homes, businesses and more within 37 blocks of West, Texas, a town 20 miles north of Waco.