A surge of immigration arrests is putting California’s “ICE-free” rules at jails and hospitals to the test, as agents continue to use county property despite local resolutions telling them not to, the San Francisco Chronicle reported.

The conflict peaked in Alameda County on Monday, the Chronicle said, when interim County Counsel Andrea Weddle sent a cease-and-desist letter to ICE’s San Francisco field office demanding that agents stop staging and making arrests in county lots, especially around Santa Rita Jail in Dublin. The letter described a Sunday confrontation in the jail lobby and a Nov. 1 chase from the parking lot into the lobby that ended in an arrest, and said agents have ignored deputies’ orders to leave. An ICE spokesperson told KALW that agents are conducting lawful enforcement. Alameda County already adopted a resolution this year barring the use of county property as a staging area, processing location or operations base for civil immigration enforcement. Supervisor Nikki Fortunato Bas told the Chronicle that counties across the Bay Area have been on “high alert,” with more arrests and more visible ICE activity around the midterms.

In Santa Clara County, the Chronicle reported, ICE began parking at the Elmwood jail in Milpitas in mid-October, and agents tased a man after a release on Oct. 28. Last week the Sheriff’s Office restricted access to the Elmwood lot, blocking most entrances and checking IDs, after what officials described as safety concerns including a high-speed chase in the parking lot. Sheriff Bob Jonsen said the goal was to “maintain a safe and secure environment for everyone who comes to Elmwood.” County Counsel Tony LoPresti told the Chronicle on Tuesday that the lot was still locked down, that agents have continued enforcement on nearby streets, and that overall enforcement decreased once the lot was closed to the public. Monterey County sent its own cease-and-desist letter on Nov. 5, the Chronicle said, after agents blocked parking at Natividad Medical Center and forced a temporary shutdown of jail operations in a shared lot.

The Alameda County Immigration Legal and Education Partnership told the Chronicle it has confirmed 19 arrests across the county in the last four weeks, including four in Oakland on Saturday and three near Santa Rita. Volunteer Renee Coe called the post-election period “a huge escalation.” Immigration attorneys have warned clients with nonpermanent status to be cautious about visiting jails, the Chronicle reported, and Alameda County has scheduled a Dec. 7 hearing on an October incident at Highland Hospital in which staff later questioned whether the hospital met state limits on sharing information with ICE.