(Tacoma, WA)  --  Police say a standoff with a man who's believed to have shot a Tacoma police officer to death is over.  Authorities say the suspect was shot and killed by police during the standoff around 3:30 this morning.  Investigators day the officer died around nine o'clock last night at a hospital.  The 17-year veteran of the Tacoma Police Department was shot several times while responding to a domestic-disturbance call in the 400 block of East 52nd Street.  The name of the officer and the name of the suspect haven't yet been released.