  The s-wave meson-baryon interaction in the $S = -1$ sector is studied by
means of coupled-channels, using the lowest-order chiral Lagrangian and the N/D
method to implement unitarity. The loops are regularized using dimensional
renormalization. In addition to the previously studied $\Lambda (1405)$,
employing this chiral approach leads to the dynamical generation of two more
s-wave hyperon resonances, the $\Lambda(1670)$ and $\Sigma(1620)$ states. We
make comparisons with experimental data and look for poles in the complex plane
obtaining the couplings of the resonances to the different final states. This
allows us to identify the $\Lambda (1405)$ and the $\Lambda(1670)$ resonances
with $\bar{K}N$ and $K\Xi$ quasibound states, respectively.
