Inclusive four-jet events produced in proton--proton collisions at a center-of-mass energy of 7 TeV have been analyzed for the presence of hard double parton scattering collected with the ATLAS detector. The contribution of hard double parton scattering to the production of four-jet events has been extracted using an artificial neural network. The assumption made was that hard double parton scattering can be represented by a random combination of dijet events. In addition, a sample enriched with double parton scattering events was extracted and several characteristics of these events were studied. The measurements have been compared to different MC generator predictions.