The powerful flare of 4B/X17.2 on 28 October 2003 in the NOAA AR 10486 active region is explored by using H_α-filtergrammes. Having a (βγδ-complicated magnetic structure and sigmoidal pattern of the polarity-inversion line, the above-mentioned AR reached its maximal dimensions at the 23th cycle. This AR also consisted of local filaments, loops and systems of loops. The light curves obtained for all of the flare knots clearly reveal two stages of evolution. The first stage is pre-flare, with storage of unpotential magnetic energy (energy of electric currents) became over with preparation (of necessary and complete conditions) for the realisation of the second stage. One may observe slow and slight intensity change of all the flare knots (except one) and the activization of structure creations (twists and connections) at this stage. Emergence of a new magnetic current promoted the creation of interconnected filaments and loops (IFL) system at either the central part of AR or its edgest at the end of the first stage. New flare knots began appearing around the main S-like filament. The second flare stage began with a dramatic increase of intensity and square of all flare knots and the creation of new knots at 11:02 UT. The main part of AR was covered by a flare emission around the main filament during 8m. At the maximum of the flare’s radiation intensity fluctuational behaviour manitests itself. One may have observed a slow intensity decrease at every flare knot after the maximum (decaying phase). The IFL system (by means of the magnetic reconnection) transformed its storaged magnetic field energy into a strong emission of electromagnetic and corpuscular radiations having covered all the AR.