(Happy Valley, OR)  --  Police are looking for a woman wearing a fake mustache, who robbed a bank and threatened to set off a bomb in it.  Authorities say the incident happened around 3:35 yesterday afternoon at a US Bank on Southeast 82nd Avenue in Portland.  Investigators say the woman, who had her hair tucked under a red baseball cap, did not display a weapon.  The suspect is described as Hispanic, about five-foot-three, 100 pounds, wearing a black long-sleeve shirt and black saggy pants, and carrying a black backpack.