SsT Reactions question


Hello there , probably a dumb question . But i have to ask it to clear up a argument .
In the Rulebook it states that a reaction can be made for a opposing enemy , having an action within X inches .
It says that the models come out of Alert status and can shoot,beat feet, screech ect.
Is this a infinite ability ? or is it allowed only once per turn i.e
Arachnids unit A attack-marines squad A reaction , arachnid unit b attacks -marine reaction squad A , and so on to evade close combat.
If this can be cleared up i would appreciate it.
you may only "beat feet" once per turn. The rules say to turn the figures around as a reminder they may not flee again.

You may shoot as many times as you react, provided that you don't suffer "out of ammo" results