Arizona’s Sawmill Fire grew to 40,000 acres on Thursday, April 27, doubling in size in 24 hours.

According to KTAR, the fire was started when an off-duty Border Patrol agent was shooting recreationally. The agent wasn’t named, but did report the fire right away, agency spokesman Christopher Sullivan told KTAR.

This video from Golder Ranch Fire District shows the wildfire, taken at 8:30 pm on Wednesday.