Bonjour John,
Thanks for your question!
When talking in a general context, French people would use the term la police rather than la gendarmerie, as such:
La police va arrêter le criminel.
Actually, as a French speaker, I find that la gendarmerie refers more to the station than the people.
In this case, we would rather use les gendarmes when talking about them, so the following answer is also correct:
Les gendarmes vont arrêter le criminel.
I hope that's helpful.
Merci et à bientôt !
