Firefighters and hazardous materials crews responded to an explosion Monday morning at the 130,000 barrel per day (bpd) Valero Houston refinery, according to KHOU-TV. REUTERS/Graphics

HOUSTON (Reuters) - Valero Energy Corp said production at its 130,000 barrel per day Houston refinery was temporarily reduced after an incident that heavily damaged a sulfur loading tank on Monday morning.

The Houston Fire Department said the tank, which contained sulfur dioxide, ruptured, leading to a shelter-in-place order to nearby residents in Houston’s Manchester neighborhood. The shelter order was lifted about two hours after the incident.

A total of five workers -- three contract employees from the refinery and two contractors from nearby facilities -- were taken to hospitals following the incident with breathing problems.

All had been released by mid-afternoon, the company said.

Earlier Valero said four workers were taken to hospitals.

Small homes in the Manchester neighborhood are across local streets from the refinery, which is at the west end of the Houston Ship Channel.

Local television station KHOU-TV showed video of a smoldering tank with a large hole in a portion of its roof at the refinery in a Monday morning news report. Debris could be seen on the ground near the tank.