Freddie Foreman was involved in that raid. By Foreman's account, Dighton said he thought he'd fired five shots, the first two of which were meant as a warning. Foreman says that the second 'warning shot' in fact hit one of his 'firm' in the head, unseen by Mr Dighton, and the fourth round struck another one in the arm.
The man with the head wound died at some point, possibly in one of the getaway vehicles, and other sources suggest that the dead man was buried in a field somewhere (Foreman doesn't comment); the story was then put about that the dead man had absconded to Australia with a mistress, hence his disappearance from the scene.
Foreman claims that it was rare for 'firms' to go out armed with firearms at that point, and the revelation that the banks had been allowed to arm some of those accompanying security vans was the point at which the 'armed blagger' so beloved of Regan and Carter came on the scene with a vengeance.