We present a study of the high energy spectra of hadrons in cores of extensive air showers. These data were obtained for the first time in the hybrid {\it HADRON} experiment (Tien-Shan) by means of a large X-ray emulsion chamber combined with the shower array. In the local energy interval 3--100 PeV an increase in the energy of hadrons was found, which means the appearance of a penetrating component. This component in our experiment was observed in the atmosphere that indicates the presence of a penetrating strongly interacting component in primary cosmic rays. Along with that, it is worth emphasising that the region where this component is observed coincides with the region of the so-called knee in the spectrum of cosmic rays. On this basis, a new hypothesis of knee formation can be put forward.