The cause of an explosion and fire at a chemical processing facility in Valdosta remains unclear.

A city spokeswoman said elevated pH levels of water inside the Perma-Fix facility delayed some of the on-site evaluations that need to be performed there. The pH level is used to determine the level of acidity in water.

Valdosta fire officials have said more than 40 firefighters responded to the Wednesday afternoon blaze and three people were severely burned.

The Department of Labor's Occupational Safety and Health Administration is investigating. The Environmental Protection Division is also looking into potential environmental concerns that may arise because of the explosion, fire and possible chemical run-off into a nearby swamp.

Tags: Valdosta, explosion, Georgia Environmental Protection Division, investigation, chemical plant, U.S. Occupational Safety and Health Administration, perma-fix