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At least two people were hurt and another missing after an explosion and large fire erupted Thursday morning at a chemical plant southwest of Fort Worth, Texas, authorities said.

Most of the dozen employees made it out safely at the time of the incident, which was called in around 9:45 a.m. CT (10:45 a.m. ET), according to the Fort Worth Fire Department. A witness described a "big kaboom" sound, according to NBC Dallas-Fort Worth.

"Things were blowing out of the roof, like metal lids on buckets. Then, the fire," Jesse Bailey, who was working next door, told the station. "It smells like sulfur," he added.

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Fire officials said crews were not being sent into the building in order to let the blaze burn out. At least one more explosion was captured by cameras above the scene.

NBC 5's Texas SkyRanger just captured another explosion at the chemical plant fire in Cresson. Watch live ➡️ https://t.co/rWCiAKtQxp pic.twitter.com/C4EeQx86Jy — Frank Heinz IV (@frankheinziv) March 15, 2018

Other fire departments were en route as well, but firefighters remained cautious in the event of further blasts, Cresson Mayor Bob Cornett told NBC Dallas-Fort Worth.

Hood County Sheriff Roger Deeds could not immediately provide the extent of the injuries, but one person was badly burned and transported via air.

A part of State Highway 171 was closed because of the fire. Plumes of black smoke could be seen coming from the plant, which appeared to belong to Tri-Chem Industries, which is responsible for taking chemicals off railways, repackaging them and sending them back out. The company did not immediately comment about the incident.

Hood County Sheriff's Lt. Johnny Rose said fertilizers were not stored at this location.

Johnson County Emergency Management tweeted that smoke was blowing away from Johnson County, but that officials would continue to monitor wind direction.

Texas has been the scene of other plant explosions in recent years, including one in Crosby last summer after Hurricane Harvey and a massive fertilizer plant fire in West in April 2013 that claimed 15 lives.