Could someone help us out with a War of the Ring rules question?

Regarding the Shoot Phase…
Are shooting attacks considered to be simultaneous or Sequential?
For example,

Assume there are to two formations facing off (each with one full strength company)
Formation A and Formation B

Formation A has priority and shoots first (A=8), inflicting 2 casualties.
When Formation B shoots back, do they get to shoot with 8 or 6 attacks?
Simultaneous = 8
Sequential = 6

Many thanks.