Mastiles, I too hope the Police response was based on more than guesses and assumptions given that it was an informant/witness led response. I've only chucked in my two penneth based on the little information contained within the story.
Knowing how these things pan out and considering the gravity of the consequences if this type of information was ignored, the informant would have been thoroughly interrogated, including questions to gauge their knowledge of firearms, the authenticity of their account, whether the informant is truly independant/unbiased and honest. Based on what the Police have, a tactical plan would have quickly been formed. This tactical plan could be anything from do nothing but surveil the alleged offender, send local un-armed officers to attend to assess, to a full blown control of the terminal. But certainly the Police cannot afford to ignore this kind of information.
MrSalmon, unless you actually see a gun with your own two eyes, I don't think you can ever be "sure", but you'd certainly have reasonable suspicion. Lets face it, the response to these type of incidents is based upon the same type information that people are sent to prison. That is, witness accounts. The difference is that in a sponataneous firearms incident you don't have the benefit months of investigation and reflection to fall back upon. Again, it would be based on reasonable suspicion derived from witness accounts.
