According to the Illawarra Mercury, mine staff isolated the power from the containers and called emergency services at 7.25pm.
Southern Highlands Rural Fire Service district superintendent Martin Surrey told the newspaper that crews found the two storage containers “well alight” when they arrived.
“It wasn’t too difficult to isolate the fires and put them out,” he reportedly said.
“Getting water to the site was the main priority for our vehicles but once they established lines, it was quite simple to put out.”
Surrey reportedly said there was little risk the fire, which took more than an hour to put out, could spread and said no one was injured.
An electrical fault was thought to have caused the fire.
Fire and Rescue NSW crews also attended the fire with an estimated 50 firefighters involved.