ATCTimmy.. You're so excitable I simply do not believe your profile, which says you work in ATC.
I do not believe that the fire vehicles were being pursued by the police - what were they going to do, nick them for speeding?? There is nothing remotely exciting about the emrgency services positioning themselves at designated positions along the runway. It happens very frequently for many reasons. If, as you claim ,you were listening to it on the radio you should know what it was all about anyway.