It’s common knowledge that helium can make someone’s voice sound like a chipmunk, but the gas may be capable of another unexpected trick as well—doing serious damage to Apple products.

At Morris Hospital in Morris, Illinois, the installation of a new MRI scanner coincided with 40 different Apple devices, including iPhones and Apple Watches, experiencing glitches. Some of the equipment completely died, according to a report from iFixit.org.

“My immediate thought was that the MRI must have emitted some sort of electromagnetic pulse (EMP), in which case we could be in a lot of trouble,” Erik Wooldridge, systems specialist at the hospital, said, as quoted by iFixit.org.

It wasn’t an EMP, however—the hospital eventually determined it was a helium leak, from liquid helium used to keep the MRI scanner cool. While most of the equipment did eventually recover, one iPhone and numerous Apple Watches appeared to suffer permanent damage.

Read below for the full story, including additional research into the science behind this occurrence.