A concerning new modus operandi, although this foiled attack was in Istanbul, Turkey it is possible it could be replicated globally. IED's placed in vehicles in shopping centre carparks, and also in previously purchased and returned Microwave ovens, suicide vest and firearms were also recovered indicating a marauding attack was to be included. This methodology is something all retailers need to consider as a potential risk and how their processes relating to returns can present a harder target.
Below is the full advisory for UK National Counter Terror Police. It can be downloaded from here.