Kice said today's actions are part of an investigation related to gang activity but said she could not yet give specifics.
"We are out executing search and arrest warrants related to this case," Kice said.
The activity began this morning and was ongoing as of about 10 a.m., she said.
Kice did not say where in the Bay Area the warrants are being executed and declined to confirm reports that some of the activity is in San Francisco.
She said more than half a dozen federal, state and local agencies are involved in today's actions.
He said the assistance was related to a major investigation into MS-13, or Mara Salvatrucha, a notorious street gang.
He referred other questions to ICE.
San Pablo police could not confirm whether any ICE activity had happened in their city this morning.
Kice said gang-related ICE investigations generally fall under the umbrella of Operation Community Shield, an "overarching initiative" aimed at combating gang activity.
A description of Operation Community Shield posted on ICE's Web site states that the operation initially focused on MS-13 but expanded in May 2005 to include all transnational criminal street and prison gangs.