According to police in Gimhae, South Korea, a 60-year-old patient was killed last week when a 60-kilogram oxygen tank was sucked into the MRI machine where he was being scanned.

The man, who has not been named, was admitted to the MRI suite in a hospital late on Thursday in a critical condition, suffering from seizures.

“We’re investigating why the oxygen tank was brought into the room,” Police Superintendent Choi Tae-yong told This Week in Asia, adding that the inbuilt oxygen supply system may have been malfunctioning. “We will thoroughly investigate the incident to determine whether human errors were involved.”

Projectiles are one of the biggest dangers associated with MRI scanners, as the strong magnetic fields generated by the machines—which are up to 60,000 times stronger than the Earth’s magnetic field—attract metal objects and cause them to become airborne.

Read the full article at South China Morning Post.