We observe the new phenomenon of anomalous prolonged time distributions of neutron intensity using the 18NM64-type neutron monitor operating together with the shower installation of the Tian-Shan mountain cosmic ray station. We observe anomalous events in the core region of extensive air showers (EAS) with the size N_e > 10⁶. The threshold of their generation coincides with the knee in the energy spectrum of primary cosmic rays (about 3 × 10¹⁵ eV). The prolonged neutron events are accompanied by the flows of EAS electrons and γ-quanta having time distributions similar to those of the neutrons. The discovered phenomenon may be a reason to make a principal change in the usual procedure of EAS exploration.