  We report on a study of the finite-temperature chiral transition on an
$N_t=4$ lattice for 2+1 flavors of Kogut-Susskind quarks. We find the point of
physical quark masses to lie in the region of crossover, in agreement with
results of previous studies. Results of a detailed examination of the
$m_{u,d}=m_s$ case indicate vanishing of the screening mass of $\sigma$ meson
at the end point of the first-order transition.
