That's better, but it's still a mystery. Cs-137 sources should be rigorously stored, even in density gauges they are permanently inside a capsule with a shutter that turns the beam "on and off". It's not like you have a chunk of Cs-137 rattling around in a drawer somewhere (or worse, somehow in powered form that gets all over the inside of a shipping container) but that sounds like that's been the case here.
It's not the first time one of these sources has come loose though - there was a capsule lost on 1400km of highway in Western Australia a little while ago.