I'm more concerned about the Detasheet material, although the C4 is worrisome enough.
The problem is that it's so easy to slip a pre-cut Detasheet into a FedEx, UPS, or Express Mail envelope. I won't go into the possibilities of detonation triggers, but they're not too hard to imagine.
I hope they run these thieves down before they can wreak their havok. In the meantime, if you or your business might possibly be a potential target for any reason, be very careful with express courier deliveries over the next few weeks.
This is potentially a very dangerous situation.
Known by many trade names, such as Metabel, Deta sheet, Series 1000 - PETN sheet explosive, and Series 2000 - RDX sheet explosive. These plastic bonded explosives have a very high brisance and detonating velocity. Sheet explosive is in most cases the explosive of choice for the tactical loading of the HYDRO CUT Entry and Gun Port Frames. Sheet explosive is supplied in North America in rolls which are a standard 10 wide. Depending on the thickness of the sheet explosive it is supplied as two X 10 pound rolls per box, or two X 20 pound rolls per box.
(snip tabular information)
Sheet explosive should be cut with a knife, not with scissors or shears to avoid potential injury. Both Series 1000 and Series 2000 are cap sensitive explosives.
http://science.howstuffworks.com/c-41.htm for the more curious.
Slipping it into a package is easy, getting it to go off, not so easy. It takes several bricks (Army issue 1/2 kilo blocks) to blow a truck.
A 150 pounds, a lot of weight, unless several folks are involded, so, not easy to carry....in the trunk of a car - could make quite the mess.
Hopefully the local heat will recover the goods quickly.
Just in time for Christmas.