ICE agents arrested 10 alleged members of the El Salvador-based gang Mara Salvatrucha, or MS-13, according to the agency, along with 11 other people detained solely on immigration charges. As of Friday, all but one of those detainees had been released.
Daly City's mayor said the operation was a "complete surprise" to him.
"ICE has never reached out to me, and basically I feel I've been left in the dark," Mayor Glenn Sylvester said.
The action in Daly City took place on Rio Verde Street near the Cow Palace, which is at the city's border with San Francisco.
Daly City police say they assisted ICE in an early morning operation there -- the serving of a search warrant. The department was told the work was part of a criminal investigation and not tied to immigration enforcement, police Sgt. Ron Harrison said.
Police and ICE officials were unsure how many detentions occurred in Daly City.
Harrison was unable to confirm a report by ABC 7 that a dozen people were located inside the Daly City residence at the time of the raid.
Daly City Police Chief Manuel Martinez is trying to find out how many people were detained at the scene and if any of them were undocumented immigrants with no ties to the gang, said Harrison.
ICE spokesman Schwab said over the weekend he, too, is trying to find out how many people were detained in the Daly City raid.
Daly City Vice Mayor Juslyn Manalo, who was briefed along with the mayor by police officials only after the uproar in Santa Cruz, said she wishes she had learned about the raid earlier.
"That's a concern to me ... that it was not communicated to the mayor or to myself and my other colleagues," Manalo said.
The City Council on Monday is scheduled to vote on a resolution, affirming the police department's policy of not enforcing federal immigration laws. The resolution says that local police will help ICE only in combating crime, not in targeting undocumented immigrants.
"We support our immigrant community," Manalo said. "Daly City is a safe haven."
Daly City's policies are similar to those in other so-called sanctuary cities but the word "sanctuary" is not in Monday's resolution. City leaders are considering changing that, Manalo said.
"When these incidents occur, it concerns me," she said. "I want our community to know that they should feel safe."