MONT BELVIEU, Texas — Explosions and fire ripped through a Houston-area petroleum plant, leaving one person unaccounted for Tuesday afternoon, officials said.

Explosions were heard about 12:15 p.m. at Enterprise Products on Sun Oil Road in Mont Belvieu, about 35 miles east of Houston, NBC station KPRC reported.

The company told KPRC the fire broke out at its west storage facility, and there was an abnormal reading in the plant's command center shortly before the explosion.

Bright orange flames consumed a large part of the natural gas liquid fractionation plant, which also provides storage and makes octane-boosting gasoline additives, KPRC said. Thick black smoke filled the air as TV images showed flame-engulfed vehicles parked adjacent to the plant.

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Mont Belvieu Mayor Nick Dixon told msnbc cable TV that flames could be seen for 7 miles.

The Weather Channel reported winds from the east-southeast with gusts up to 32 mph whipped the inferno.

One contract worker was unaccounted for at the plant, where 600 to 700 work, Enterprise Products spokesman Rick Rainey told CNN. Burning natural gas posed no environmental hazard, he said.

The flames were not near homes, Dixon said.

"You could hear the liquid gas coming out of the ground making that woosh sound," one witness said.

The company said it was shutting down valves but did not estimate how long it would take for the fire to burn itself out.

The nearby Barbers Hill Independent School District ordered students to stay indoors as a precaution early in the day but later resumed normal operation.

Nearby streets were closed as flames reached an estimated 500 feet into the sky.

The facility separates natural gas liquids into different components before storage or injection into pipelines, the Houston Chronicle reported. It has a capacity of about 305,000 barrels of natural gas liquids per day.

The Mont Belvieu site also has 34 underground caverns with capacity to store 100 million barrels of products — or almost a year’s worth of produced natural gas liquids such as ethane, propane and butane, the Chronicle said.

The plant is north of the Houston Ship Channel and its row of crude oil refineries. The blaze was having no effect on Ship Channel operations on Tuesday afternoon, the U.S. Coast Guard told Reuters news agency.

Salt dome woes
Mont Belvieu is a major natural gas storage and processing hub sitting atop a salt dome formation. The natural gas industry stores more volatile hydrocarbons there than anywhere else in the world, NBC News said. The area is like an egg-shaped mound on the coastal prairie.

The nearby community of Barbers Hill, with population 200, was bought out by the industry during the 1990s after a series of explosions at Warren Petroleum.

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NBC News cited geologists with the Texas Bureau of Economic Geology at the University of Texas saying salt dome storage poses three risks: A pipeline or well may leak and cause an explosion; toxic chemicals stored in the domes could leak into local water supplies; or land and aquifers may be contaminated by salt water left from carving and refilling the caverns.

As the number of storage caverns in Mont Belvieu's salt dome grew, so did the town's problems, NBC News said. Explosions and gas leaks plagued the town throughout the early 1980s. In July 1986, water with five times the saltiness of ocean water crept into the drinking water supply.

A coalition of area petrochemical companies bought out 200 families in the town later that year, NBC News said. Mont Belvieu shifted its town center about 2 miles down the road.