The Normal Fire Department responded to a fire on May 28 at Rivian’s assembly plant in Illinois. No injuries were sustained during the incident and damage was minimal but it is the third such fire that the plant has suffered in seven months.

The NFD said in a statement that the cause of the fire was a defective battery pack that ignited inside the Rivian Automotive plant. When firefighters arrived, the pack was inside the building experiencing thermal runaway in the battery testing area.

“We evacuated a portion of the Normal Plant on Saturday as standard practice during a thermal event affecting a single battery pack,” a Rivian spokesperson told us in an email. “The pack had already been identified as faulty and was undergoing additional testing when the event occurred. Our Environmental, Health, and Safety team is investigating the cause with our engineering team and the Normal Fire Department, which responded promptly.”

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The fire department was successful in extinguishing the flames inside the plant and, once it was cool enough, they took the damaged battery outside where they continued to cool it until it was safe to release back to Rivian engineers for investigation and disassembly.

“The exact cause of the fire is under investigation, but the battery pack had been in a repair area and was being tested when the thermal runaway began,” the department wrote in a statement. “The fire was in the battery assembly area and did not involve a vehicle or production equipment.”

Fortunately, no one was injured and damage was limited to the battery pack, the carrier, and the test booth equipment. Firefighters were on the scene from 10:38 am until about 2:00 pm.

Although the fire’s impact on the plant was mostly limited, it remains noteworthy for having been the third in less than a year. In February, the Normal Fire Department responded to a fire that involved a vehicle that caught fire in the plant and caused an evacuation. On October 26, meanwhile, it attended to a “small fire” that ignited in an automated battery assembly area. The department remarked that the damage from the October fire was negligible and, again, injured no one.