Medical staff had to halt the procedure, fearing a possible explosion. The hospital, unfamiliar with such protocols, immediately alerted the authorities, and around 1:40 a.m., police arrived and activated the bomb squad. The team established a security perimeter to neutralize the device so surgery could continue, though no one knew at that stage if the entire operation could blow up at any moment.
are shells explosive or just heavy/huge bullets? I know the ones with the tiny button on their nose, but I thought it was during WW2.
edit : https://en.wikipedia.org/wiki/Shell_(projectile)#High-explosive_shells
actually it was already explosive before WW1