Williams Companies down after plant explosion

Shares of Williams Companies slip after plant explosion and fire in Louisiana

The Williams Companies Inc.'s shares fell Thursday after an explosion at one of its plants started a fire.

THE SPARK: Louisiana State Police said that an explosion at The Williams Companies Inc.'s chemical plant in Geismar started a fire Thursday morning. The plant makes highly flammable gases that are basic building blocks in the petrochemical industry.

THE BIG PICTURE: While injuries have been reported, the company said that the number and extent of those injuries is not known at this point. Officials say ambulances and helicopters have taken at least 30 people from the burning plant.

The town is about 20 miles southeast of Baton Rouge. Residents in the surrounding area have been asked by state police to stay indoors and close all windows and doors.

Williams said in a statement that emergency shut-down valves have been closed and the unit is isolated. It also said it is in the process of accounting for all personnel.

It's unclear what the scope of the situation is or what impact it may have on the company, but with the recent deadly fertilizer plant explosion in Texas, investors may be extra jumpy.

SHARE ACTION: Williams Companies shares fell 12 cents to $33.91 in midday trading, amid a broader market uptick. The stock fell to $32.54, a 4.4 percent drop, earlier in the session.

The company is also a controlling partner in Williams Partners L.P., which owns most of the Williams Companies' pipelines. Shares of Williams Partners fell 98 cents to $48.69.