The victims, a man and a woman in their 50s, were walking along Chilco Street west of Constitution Drive at 6:54 p.m., Cmdr. Dave Bertini said.
A car driving east behind them struck them from behind, launching them in the air and onto the street. The car then swerved across the center divider, hit another car, and slammed into a tree, Bertini said.
Police arrived and found the couple dead at the scene and the dog they were walking injured.
The suspect's car was still against the tree when police arrived and the driver, identified as Marjorie Reitzell, 54, of Redwood City, was taken to Stanford Hospital, Bertini said.
Investigators determined that Reitzell had been drinking and arrested her at the hospital. Once she is released she will be booked into jail on suspicion of two counts of gross vehicular manslaughter and DUI, Bertini said.
The car that Reitzell allegedly struck remained at the scene. No one inside was injured and the vehicle sustained only minor damage, Bertini said.