If you're level consists of combine arresting citizens as your going along.
(by this i mean that it doesnt happen as a trigger, it happens if a citizen gets too close to a combine or whatever). There is a sequence for citizens that is called "arrest" or something like that, you would at least have to trigger that with a scripted sequence. Best bet to do this is to add an output from the citizen like:
input: OnDamaged
Target entity: Scripted_sequence
Output: Start sequence (or watever the outputs called
)
Set your scripted sequence to target the citizen and customize all your settings (including the actual sequence)
The only problem is that if anything damages the citizen it will trigger the sequence, so unless the only enemy within your citizens reach are metrocops or combine without guns, it would be a lot better to use Choreo scene to arrest one citizen and just make the atmosphere sound like the combine are arresting citizens.