(Portland, OR)  --  A woman is under arrest after allegedly ramming a Portland police patrol car with a stolen vehicle.  Elizabeth Hefner was arrested yesterday following the alleged incident that took place just after 4 p.m. near Washington Street.  Hefner allegedly fled the scene with several passengers in her vehicle before police started to chase them down.  Police say two of Hefner's three passengers were arrested on unrelated warrants, but Hefner was taken into custody after being found hiding in a trash dumpster.