"We are actively seeking witnesses to the incident who have not come forward or been identified to assist us," said Los Gatos Monte Sereno police Sgt. spokesman Clinton Tada.
Police are on the lookout for an African American adult in his early to mid-20s, standing 5-foot-9 to 6-feet tall with a slender build and short brown hair who attacked a mother dropping off her child at Dance Attack! studio in Los Gatos shortly before 4 p.m.
The suspect was last seen wearing a white T-shirt, blue jeans and a white baseball cap backwards. He remains at large, police said.
The assault took place in the 1400 block of Blossom Hill Road at the Harwood Shopping Center when the suspect confronted the woman in a strip mall parking lot and struck her in the face with a single closed fist, according to police.
The incident is currently being investigated as an assault/battery although it has "similar characteristics" to the sick and violent so-called "knockout game" phenomenon, Sgt. Tada said.
The crime is described as assailants attempting to knock out unsuspecting victims with a single sucker punch for amusement purposes.
Los Gatos residents are asking police if the incident is related to the recent phenomenon where assailants attempt to knock out unsuspecting victims with a single sucker punch for amusement purposes.
"No definite motive has been identified at this point in the investigation," he said.
Townsfolk and the general public are advised to be aware of their surroundings, identify who and what is around them, and, if at all possible, accompany themselves by other persons when walking in desolate areas, Sgt. Tada said.
If suspicious subjects are seen in areas loitering or committing suspicious activity, call 911 or the local police department at 408-354-8600.