CHICAGO -  An explosion at a chemical factory in the southern US state of Louisiana injured at least 33 people on Thursday, officials said.
There were reports of fatalities within the plant but they have not yet been confirmed, said Jean Kelly, a spokeswoman for the state's department of environmental quality.
Huge black plumes of smoke and orange flames could be seen billowing out of the plant in Geismar, a small town north of New Orleans.
Approximately 30 people were transported to area hospitals by ambulance and three others were evacuated with helicopters, Kelly told AFP.
People within a two-mile radius were told to stay inside, close their windows and shut down air conditioning units to protect themselves from the potentially toxic smoke.
"We've completed our first round of monitoring," Kelly said. "We didn't see any spikes of chemicals in the air."
The explosion happened just before 9:00 am (1300 GMT) at the Williams Olefin plant, the local government said in a statement on its Facebook page.
"No 'extremely hazardous materials' were involved in this incident up to this point," the Iberville Parish Council said.
The facility produces approximately 1.3 billion pounds of ethylene and 90 million pounds of polymer grade propylene a year, according to the company's website.