"There was the appearance of mosh pits breaking out where people were doing a lot of banging around and it looked like ... from the on-looker's prospective and even from some of the MPs ... that there was a fight going on," Public Affairs Officer Col. Kevin Arata said.
YouTube video has surfaced showing MPs trying to break up the mosh pit during the rock band performance.
Military leaders say they used pepper spray to gain control of two individuals. That then caused the band's lead singer, Pete Loeffler, to stop playing in the middle of his song and come to the aid of the mosh pit dancers.
"Hey, no need to pepper spray anybody," said Loeffler during the concert. "We're just having fun ... this is a rock show. This is what we do at rock shows."
Military leaders say the MPs tried to use voice commands and hand and arm signals to control the crowd, but that didn't work.
"And so as a last resort, they actually had to use pepper spray to quail what was going on out there in the crowd," Arata said.
After two individuals were escorted out, the video shows MPs kind of stood back and they let the mosh pit continue.
Investigators say the YouTube video doesn't show the MPs real concern at the family oriented event.
"And so they had some small children up there and these smaller kids where getting pressed up against these rails, while people are thrashing about in their ... in this mosh pit," Arata said. "And they thought, 'this is a dangerous situation. What are we going to do to stop it?'"
The two individuals were detained for a couple of hours and released. No charges were filed.