At least two employees were injured in a fire raging at TPC Group's chemical plant in Port Neches, Texas, early on Wednesday morning following a massive explosion felt 30 miles (48 kms) away from the plant.
There were several explosions at the plant, with fires now blazing. Crystal Holmes, Captain at the Jefferson County Sheriff's office said they were "able to pull two injured employees out" and take them to local hospitals for assistance, adding there could be more injuries.
A half-a-mile radius evacuation has been ordered, Holmes said.
"There is search and rescue inside the plant but there is also damage to nearby homes so we'll be going door-to-door checking on these people and their homes."
Firefighters were battling to contain the fires and the initial explosion was followed by secondary blasts, said five sources.
A company spokesman was not immediately available to discuss the blaze.
The Port Neches plant can produce more than 900 million pounds (408,233 metric tons) of chemicals, according to the company's website.
The first explosion occurred at the 1 a.m. local time (0700 GMT) the sources said.
The force of the blast shattered windows and blew locked doors off their hinges, the sources said.