Police believe the same man is responsible for three such robberies since Sept. 8. The most recent occurred Sunday night.
The man is described as black, between 20 and 25 years old, about 5 feet 10 inches tall, and weighing 180 pounds, police Agent Dan Ryan said. He wears a white cloth on his head and attacks women walking alone late at night near the station, takes their bags and then leaves.
"It seems to be the same guy, the methods are identical, the time of day is the same, and the witness descriptions are similar," Ryan said. "It definitely looks like a trend."
Palo Alto has had an overall increase in strong-arm and armed robberies in the past few months, and patrols have been added in response, Ryan said. There have been 14 incidents since June 20.
In addition to the three robberies near the California Avenue station, there have been four strong-arm robberies near the Palo Alto Caltrain station on University Avenue.
"We are putting all of our available resources out there to combat the problem," Ryan said.