Partygoers stampeded to escape gunfire that killed one college student and wounded 11 people at an Ohio fraternity house, authorities said Monday as they searched for a motive in the weekend shooting. Jamail E. Johnson, 25, a senior at Youngstown State University, was shot to death early Sunday as he tried to separate two groups at an Omega Psi Phi fraternity house party. Authorities say there had been a dispute, two men had left the house and then returned and sprayed bullets into the crowd. Among the injured was a critically wounded 17-year-old.