Observation of B to K_S⁰ pi+ pi- and Evidence for B to K*pm pi mp

We report on a search for charmless hadronic B decays to the three-body final states, K0S h+ pi-, K+ h- pi0, K0S h+ pi0 (h+- denotes a charged pion or kaon), and their charge conjugates, using 13.5 fb^{-1} of integrated luminosity produced with center-of-mass energies near 10.6 GeV, and collected with the CLEO detector. We observe the decay B --> K0 pi+ pi- with a branching fraction (50 +10-9(stat.) +-7(syst.)) x 10^{-6} and the decay B --> K*+(892) pi- with a branching fraction (16 +6-5(stat.) +-2(syst.)) x 10^{-6}.