I disagree. That would unfairly single out people who happen to be walking alone.
It should read: “A suspect, or perhaps a group of suspects, committed a crime. We'd rather not say how large the group was, if even there was a group in the first place.”
No you’re talking! But I fear we are discriminating against other species here. Further refinement of the alert is needed: “ A blob of protoplasm, or perhaps a group of blobs of protoplasm, is suspected of commiting a crime. We’d rather not say how large the group was, if even there was a group in the first place.”