Proposition 9
Tag 0BLB, permanent. Cite it as [Bourbaki, Tag 0BLB].
General Topology, chapter III, § 4. Groups operating properly on a topological space; compact ness in topological groups and spaces with operators
Let be a topological group operating continuously on a locally compact space . Then if is Hausdorff it is locally compact.
Since the equivalence relation on defined by is open (, no. 4, Lemma 2), the proposition results from Chapter I, , no. 4, Proposition 10.
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.