A reaction following a fire at a Georgia chemical plant Sunday morning is forcing evacuations and road closures in the area, according to Rockdale County officials.

The fire broke out on the roof of BioLab in Conyers, Georgia, around 5 a.m. ET. Water from what officials earlier described as a malfunctioned sprinkler head “came in contact with a water reactive chemical and produced a plume,” county officials explained on their website.

CNN has reached out to BioLab, described as a manufacturer of pool and spa treatment products, for comment.

A fire broke out on the roof and firefighters were able to contain the blaze, but it reignited hours later, Rockdale County Sheriff Eric Levett said in a video message posted on Facebook.

The fire was put out around 4 p.m. ET, Rockdale County Fire and Rescue Chief Marian McDaniel said, but the plume from the chemical reaction can still be seen for miles and is causing problems for area residents. The smoke may be visible for several days, she added.

The cause of the fire, as well as the chemicals involved, remains unknown, McDaniel said.

“I want to strongly ask all of you to please spread the word to stay away from this area at this point,” Levett said. “It’s burning pretty good. We’re trying to get that under control, but at the same time we’re also trying to get the traffic under control.”

Roads are closed in the area, and residents between Sigman Road and Interstate 20 were asked to evacuate – around 17,000 people, according to Sharon Webb, director of the county’s Emergency Management Agency. Additionally, the interstate is blocked in both directions between Salem Road and Turner Hill. The sheriff said he will ask for assistance from the Georgia Department of Public Safety and the Georgia State Patrol.

Residents north of Sigman were asked to shelter in place and keep their windows closed.

Conyers Mayor Vince Evans urged residents who choose not to evacuate to stay in place and not wander or drive around the city.

“This is not the time to do any type of sightseeing. We are strongly encouraging everyone, no matter where you’re coming from, but especially Rockdale residents, to stay out of this area,” Levett added.

A local hospital began moving patients to other facilities as a precaution, and officials urged those having an urgent medical emergency to go to a surrounding hospital or one in another county, Webb said.

Rockdale County Chairman Oz Nesbitt told CNN’s Jessica Dean it’s an “all hands on deck” situation.

“All of our resources have been dispatched and deployed,” Nesbitt said. “Every available agency, GEMA, FEMA, everyone is on deck here in Rockdale County, we’re managing this situation as we try to get it under control.”

Environmental safety officials are conducting air quality tests to determine if there are any toxins in the smoke.

“We’re not taking any chances,” the chairman added.

The roof of the chemical plant building has since caved in and Nesbitt described the damage as a “complete collapse.”

Residents in neighboring Newton County on Sunday also received an alert about the situation in Conyers.

“We are monitoring the situation and would advise that if you smell a chlorine odor you should turn off your air conditioners, turn on your ceiling fans, and if possible, bring your outside animals indoors,” the message read. “If you experience any trouble breathing or any other medical emergency, call 911. As for now, sheltering in place is the best option.”

In September 2020, BioLab experienced a “thermal decomposition event” that also led to a fire that temporarily closed Interstate 20.

In its final report on the incident, the US Chemical Safety Board found strong winds from Hurricane Laura damaged the lab’s warehouse, allowing rainwater into the building. The water came in contact with a chemical and initiated a reaction that caused the fire.

Conyers is about 30 miles east of Atlanta.