Valero Energy Corp. spokesman Bill Day said four workers were taken to the hospital for evaluation, but the sulfur release was quickly contained.
He said officials do not believe the loading tank fire poses any further threat to the community.
Debris was scattered on the ground below where the tank ruptured in the Manchester area of east Houston, near the Houston Ship Channel. But the cause of the fire is under investigation, Day said.
The Houston refinery makes gasoline and gas derivatives.
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