Seventy-seven US Air Force Reserve cadets have been taken to a hospital after a lightning strike at a southern Mississippi military training base, a spokeswoman said.
Cadets from around the country were at the Joint Forces Training Centre for two weeks of work, said Army National Guard Major Deidre Musgrave.
All were responsive and stable after the lightning hit, she said.
County emergency operations director Terry Steed told a National Weather Service forecaster that nobody was directly hit when lightning hit a power pole near tents.
All were taken to hospitals as a precaution, said Mike Edmonston, a senior meteorologist in Jackson.
Camp Shelby near Hattiesburg is the nation's largest state-owned military training centre.
Its 136,000 acres include mock cities designed to look like Iraq and Afghanistan to give soldiers realistic training.