Cobb County Firefighter Denell Boyd tells WSB's Jennifer Griffies it happened around 1 o'clock at the Atlanta Diagnostics Center in Kennesaw.

"The MRI machine has an end bell, which has helium and liquid nitrogen. The pressure from the helium made the end bell come off, and it hit a wall," said Boyd.

"The end bell that blew off really could've hurt them much worse than it did. It hit the wall, and they just took what was left from the blast of the bell coming off. The bell did not hit them, it was just all the debris from it," said Boyd.

One man had shrapnel in the back of his head. Another man injured his arm. They were taken to the hospital with non-life-threatening injuries.