An explosion tore through the Williams Olefins chemical plant in Geismar, La., on Thursday, starting a massive fire and injuring at least seven.

A witness was at the scene shortly after the blast, shot a video of the aftermath which was first obtained by WAFB-TV, and then took to the Web to post it:

Eyewitness Ryan Meador spoke with local TV station WAFB about what he saw at the facility Thursday morning.

"It looked like a pretty big explosion -- it looks like Williams have taken all the precautions they can do to evacuate all the personnel. The firefighters are responding as needed,” he told the station.

The explosion took place at about 8:30 a.m. Thursday, and witnesses reported seeing a fireball rising into the air. No official fatality count has been released, but reported that authorities said it may be "very high."