Your own
post disagrees though. The wording is important here; they're asking for witnesses and information. If they were looking specifically for identities of people connected to the incident (often worded as "they may able to assist with the investigation" so as not to prematurely identify them as a suspect) they'd have said so, and it would have usually been accompanied with a description, and possibly CCTV stills if deemed proportionate.
It may all seem quite petty but the police have to be very careful about when they release information and how they request information from the public. It doesn't always make sense but the rules are there and the people responsible for press releases know them well. That doesn't stop the news/media agency from then interpreting it as "police appeal for information on attackers" but that won't be what the media release says.