So I was in a game the other day where my opponent was using an Imperial Knight.

Imperial Knight vs 4 space marines(single wound each)

In close combat he only hit ONCE.
Rolled on the D weapon table and caused FOUR wounds for that ONE hit.

The question is how many marines die? (The 2 people I talked to about it said all 4 die and so I went with it, but it seems wrong for a single Close Combat hit to potentially kill 12 models.)