MESQUITE (CBSDFW.COM) – An early morning fire at a chemical plant in Mesquite forced a half-mile evacuation zone and sent workers to the hospital.

It was around 1:00 a.m. when emergency crews were called out to Fritz Industries on Sam Houston Road.

Firefighters say bromate chemical compounds were burning inside the plant for hours. Emergency crews were able to put the fire out before sunrise and after monitoring the air determined any risk to be over.

Employees were working inside when the fire broke out. At least two of them were taken to a local hospital, but the extent of their injuries isn’t known.

Building alarms sounded as the fire broke out at the company that manufactures chemicals for oilfields. A man who lives near the plant says there was an explosion so powerful it shook the ground.

When Mesquite first-responders arrived and realized they were dealing with hazardous material, they called Dallas Fire Rescue for backup.

Fire Captain Travis Greenman says the temporary evacuation was done as a precaution. “So that they didn’t come in contact with any fumes or chemicals that could have been in the air. It’s just an area to keep everybody safe,” he said. “They do that just to make sure nobody comes in contact with anything. Once the monitoring determined there wasn’t anything there they lifted that.”

Fire officials say they aren’t concerned about runoff and will just keep crews at the site to monitor the building and keep an eye out for hotspots.

There was also a small explosion and fire at the plant in 2014. Two members of a cleaning crew were inside the building when that fire broke out but both made it out safely.