ST. LOUIS -- Federal investigators said a substandard hose is partly to blame for a chlorine leak in August that injured 63 people.

U.S. Chemical Safety Board Spokesman John Bresland said Friday that the ruptured hose contained a metal weave not normally used in chlorine transfer hoses. The Aug. 14 leak at DPC Enterprises near Festus, 30 miles south of St. Louis, prompted the evacuation of hundreds of homes and businesses, though no one was seriously injured. The plant packages chlorine to be used in water treatment.

Bresland also said five automatic shut-off valves at the plant and an overflow valve on a railway tank car also failed to work, the St. Louis Post-Dispatch reported Saturday.

Bresland said the multiple failures increased the size of the chlorine gas cloud, releasing about 48,000 pounds into the air.

Bresland said it was too early to draw any conclusions from the findings. The Chemical Safety Board expected to finish its investigation and issue recommendations by the end of the year.

The accident happened when a hose burst as workers were unloading chlorine gas from a railway tank car. The gas leaked for more than two hours.