  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.
