A tornado that ripped through the country’s largest coal mining site in northeast Wyoming left eight people injured and halted operations as first responders searched the massive open-pit site for employees and continued to assess the damage, officials said Saturday.

The tornado hit the North Antelope Rochelle Mine in Campbell County around 6 p.m. Friday during a shift change, initially complicating search and rescue efforts. But Peabody Energy, the operator of the mine with headquarters in St. Louis and South Brisbane, Australia, confirmed before midnight that all employees had been accounted for.

Cone #tornado northeast of Chugwater Wyoming @accuweather pic.twitter.com/T3prJhkIY8

— Reed Timmer, PhD (@ReedTimmerAccu) June 23, 2023

Six employees were still being treated in hospitals as of 11 p.m. Friday, the company said. No deaths were reported.

Melissa Smith, a meteorologist and hydrologist with the National Weather Service in Rapid City, South Dakota, said a storm system scattered tornadoes throughout Campbell, Natrona and Johnson counties.

“The tornadoes would form, come down, stay on the ground and come back up,” Smith said.

At the mining site, empty train cars and buses there to transport workers were blown over, according to Leslie Perkins, spokesperson for Campbell County. First responders also had to contain “various hazardous materials” that leaked after the tornado touched down, the Campbell County Fire Department said in a statement, although the agency did not provide more details about the leaks.

Peabody said operations at the mining operation about 64 miles (103 kilometers) south of Gillette would remain suspended until damage assessments at the facility were completed.

The mining site is the largest in the country, according to the U.S. Energy Information Administration. It produced nearly the same amount of coal in 2021 as Illinois and Montana combined, the fourth and fifth largest coal-producing states.

(AP)