How does a blast wave kill you?

[Michael Lewis]

I was reading Pegasus Bridge and it gave a report where a group of Brits were killed by the blast wave of a shell. The ghastly thing about it was that they were playing cards in a foxhole and were basically frozen in that position. My cousin who's in the army said that a .50 machine gun can kill you if it even hits a foot away from your head from the shock wave.

How does the blast wave kill?


Thanks,

Michael