The boy was waiting for his ride home in front of a karate studio in the 2600 block of Middlefield Road around 6 p.m. when a woman in a dark-colored sport utility vehicle arrived and said she was there to pick him up, police Agent Dan Ryan said.
The woman told the boy his mother had sent her but the boy asked her a question and determined she was lying.
The boy walked back inside the karate studio to wait for his mother, whom he told about the incident. There were no other witnesses, police said.
Ryan said the mother did not report the incident until Saturday, but said today the report appears to be legitimate. Police re-interviewed the family after the initial report and worked with the boy to create a sketch of the woman.
She is described as a white woman standing about 5 feet 5 inches tall with a medium build and shoulder-length brown hair pulled back behind her ears. The woman was wearing a dark jacket and blue jeans.
Anyone with information on the case is asked to contact police at (650) 329-2413 or the anonymous tip line at (650) 329-2190.