Lt. Hollie Connors said up to 80 masked bandits blocked the street up and down Broadway Plaza with up to 25 vehicles that had license plates covered from possible identification. Though the city began placing officers inside Nordstrom earlier this year after similar smash-and-grab robberies, no officers were on site just before 9 p.m. Saturday when the coordinated attack took place.
Three employees were injured, including one who was pepper-sprayed.
Police arrested three suspects Saturday night, at least one with a gun, as dozens more fled. Connors said they were still being held Sunday, though didn't know if they were still in custody Monday afternoon.
The robbery may have been part of a larger string of robberies happening at jewelry and other high-end stores around the Bay Area.
On Sunday night, 8 to 10 suspects with hammers hit Sam's Jewelry at Hayward's Southland Mall. About an hour later, suspects rushed high-end athletic apparel store Lululemon in San Jose's Santana Row, making off with merchandise.
Connors said it's not clear whether there's a connection. She said police believed another attempt would be made at Nordstrom Sunday night, and police blocked off ether end of the street and put its ready and react team on alert. No trouble was reported.
"I don't know if that made them divert, or what happened," Connors said. "We had some information that that same group might come back. We prepared."
Walnut Creek Mayor Kevin Wilk said the city will keep Broadway Plaza free of cars at least through the holidays.
"This is really all hands on deck," Wilk said. "We'll have more police downtown. We'll be monitoring online chatter and communicating with all our stores."
Connors said police resources and staffing aren't optimum right now, and people may be taking advantage.
"Police agencies are hurting right now, "Connors said.
She said there was an officer posted at the nearby Apple Store Saturday night, who was alerted to what were initially reported as a high number of reckless driving incidents around the plaza. Police responded quickly, but were hampered by the sheer number of suspects driving away in so many vehicles.
"We doing what we can do, with increased foot patrols on weekends," Connors said, adding that departments may need better coordination and more joint efforts.
There's also possibility of sharing intelligence resources with federal law enforcement.
Wilk said he expects more arrests as more video evidence is analyzed. He spent much of Monday in meetings about the city response, including discussions with other mayors on how to coordinate. He said the city also needs county help.
"We need the D.A. to charge and prosecute these cases to the full extent of the law," Wilk said. "If people see they're going to be caught, they'll think twice. We need to make people feel safe in Walnut Creek. We demand it."