The blast occurred at about noon at the AmeriGas Cylinder Exchange facility at 10985 FM 1485 near Waukegan Road, in Montgomery County.
The company refills propane cylinders used for outdoor grills. Officials say while tanks were being refilled outside the building, gas started leaking from the equipment out here and that led to a flash fire.
"We had approximately half a dozen fires, mostly small fires within the plant itself, but firefighters were able to bring those under control within about 15 minutes," Montgomery County Fire Marshal Jimmy Williams said.
Two employees suffered severe burns and were transported by medical helicopter to the UTMB burn center in Galveston. Five other employees were taken to area hospitals for minor burns. An eighth employee was taken to the hospital several hours later after complaining of chest problems.
The problem started when a gas line ruptured and propane started leaking out, Williams said. Moments later, flames erupted.
"Several of the employees did witness the leak and the information that we have initially is that before they could reach the emergency shut off, there was an ignition," Williams said. "We do not know what the ignition source is at this time. We are looking at that, that is part of our investigation."
We are told propane containers are typically refilled outdoors because of the way propane settles when it is released from tanks. If the leak had happened inside the plant, officials say, this could have been much worse.
Montgomery County Fire Marshal's investigators are on scene to investigate the cause of the incident. The Texas Railroad Commission, which regulates the propane industry, has been notified as well.