A huge fireball erupted from the Williams Olefins plant in Geismar, Louisiana early this morning as an explosion was set off. Over 600 people were working at the plant at the time of the explosion.

Approximately 33 people were injured in the blast that set off a fire that raged for hours. The local fire department, the sheriff’s office and a Hazmat team is at the location as is the company’s emergency response team.

Residents in a two-mile radius of the plant were told to stay in-doors during the conflagration.

The plant produces 1.3 billion pounds of ethylene and about 90 million pounds of propylene at the plant, both of which are highly flammable according to the company’s website. Testing done around the site did not reveal any dangerous levels of the chemical however.

Shares in Williams Cos fell over three points immediately after the news of the explosion hit Wall Street. Those shares have since rebounded and are about 1% lower than prior to the blast.