According to Quantum Chromodynamics Theory, highly compressed and heated nuclear matter should undergo a phase transition to a new state, called the Quark Gluon Plasma. These extreme conditions can probably be created in the collisions of relativistic heavy ions. We are looking for signatures of the phase transition to QGP such as enhancement of the strangeness production rates and reduction of the collective nuclear flow. The results of the invariant differential cross sections measurements for Λ hyperon and π\sp− meson production via track reconstruction in the Time Projection Chambers experiment BNL-AGS-E891 are presented. Comparison of our experimental data on the differential particle multiplicities for Λ and π\sp− with the cascade models ARC and RQMD is given. The shapes of the particles spectra indicate the strong collective expansion of nuclear matter. We employ the three dimensional expansion picture in order to parametrize the observed particle spectra and extract the flow parameters together with the mean temperature of the particle gas after the nuclear fluid freeze-out.