Article snippet: More than 200 people were arrested on immigration violations during a four-day operation in Northern California, but authorities said Thursday that hundreds eluded capture because of a warning from Oakland's mayor. U.S. Immigration and Customs Enforcement said officers made 232 arrests from Sunday to Wednesday arrests and renewed threats of a bigger street presence in California, where state law sharply limits cooperation with immigration authorities at local jails. The Trump administration has cracked down on so-called sanctuary policies, insisting that local law enforcement inform federal agents when they are about to release immigrants discovered to be living in the country illegally. Defenders of so-called "sanctuary" practices say they improve public safety by promoting trust among law enforcement and immigrant communities and reserving scarce police resources for other, more urgent crime-fighting needs. Mayor Libby Schaaf tweeted on Saturday that an immigration operation was imminent in the San Francisco area, including Oakland, possibly within 24 hours. It was unclear how many people would have eluded capture without the mayor's warning. Targets often elude authorities because agents don't have search warrants and advocacy groups have waged public awareness campaigns urging people not to open their doors. Other times, agents have outdated addresses or targets are not home. The federal agency's acting director, Thomas Homan, said Wednesday that Schaaf... Link to the full article to read more