We have searched for evidence of top quark production in pp¯ collisions at √s =1.8 TeV using the D0 detector at the Fermilab Tevatron collider. For an integrated luminosity of 15 pb−1, we report results of a search for tt¯ pairs in the decay modes tt¯→eμ+jets,ee+jets,e+jets, and μ+jets. From analyses of these modes we obtain a lower limit on the top quark mass of 131 GeV/c2 at the 95% confidence level, assuming standard model branching fractions and a predicted cross section for tt¯ production. We discuss the properties of an event for which expected backgrounds are small.Received 4 January 1994DOI:https://doi.org/10.1103/PhysRevLett.72.2138©1994 American Physical Society