Officials in rural Texas have begun to release details about what led to a fiery explosion at a chemical plant after lifting a shelter-in-place order in the surrounding community on Wednesday.

Geoff Harfield, president of the industrial blending facility Sound Resource Solutions in Shepherd, told reporters that a "forklift incident" triggered the blast, though he did not elaborate.

Officials in San Jacinto County said a preliminary investigation found the ignition happened when an employee noticed a container leaking with chemicals and tried to use a forklift to lift the container.

San Jacinto County Sheriff Greg Capers told reporters he was advised that diesel was burning, with the possibility of turpentine and other chemicals also igniting.

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Shepherd chemical plant flames and smoke

Officials ordered nearby residents and businesses to shelter in place and turn off HVAC systems. (KTRK)

Harfield said he could not speculate on what kind of chemicals were suspected of burning as the investigation was ongoing.

"We’ll make sure that any remediation work that needs to be done is going to be done in the right way so that there’s no effect on the community that we’ve loved for 14 years," Harfield said.

The blast happened around 8:17 a.m. at Sound Resource Solutions along U.S. Highway 59 in Shepherd. The city is located in San Jacinto County, about 60 miles northeast of Houston.

Shepherd chemical plant flames and smoke

Billowing black smoke could be seen covering the sky in the surrounding area. (KTRK)

An initial five-mile shelter-in-place order was reduced to a one-mile radius as officials assessed the scene. The order was lifted later Wednesday afternoon.

One person suffered first-degree burns to the face and second-degree and third-degree burns to the arms, FOX26 Houston first reported, citing a source. The individual was being treated at Memorial Hermann-Texas Medical Center.

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Officials said 19 employees were at work at the time of the incident.

Shepherd chemical plant flames and smoke

The blast reportedly happened at Sound Resource Solutions along U.S. Highway 59 in Shepherd, Texas, on Wednesday. (KTRK)

Harfield told reporters that all employees were accounted for after the explosion and that the injured worker was recovering.

"He’s with the right people and they’re taking care of him. He’s doing good – he was worried about us, so he’s doing good," Harfield said. "He’s going to be home with his family this evening, so that’s good news – everyone’s accounted for and everyone’s going to be OK."

Photos and video from the scene show a massive black plume of smoke billowing from the plant. 

Nearby roads were closed, and a private school was evacuated as first responders worked to control the fire. 

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On Wednesday night, the Texas Commission on Environmental Quality wrote on social media that mobile air units will continue to monitor air quality throughout the night.

"At this time, no levels of concern have been detected," the post read. "Our mobile command post will remain on site until further notice."

The Associated Press contributed to this report.