Immigration arrests of people without criminal convictions continue to soar in California, where the Trump administration emphasized its crackdown with a February sweep in the northern part of the state meant to counteract pro-immigrant sanctuary laws.

From October through March, more than 3,400 “non-criminals” were arrested by Immigration and Customs Enforcement’s California offices, the agency said Thursday.

That was a significant jump from the same time period a year earlier, which included the final 3½ half months of President Barack Obama’s term, when about 1,000 “non-criminals” were arrested by the agency through the California offices, which include San Francisco, Los Angeles and San Diego.

The San Francisco field office also encompasses Reno, Hawaii, Saipan and Guam, but most of the arrests included in the statistics come from within California.

Toward the end of the Obama administration, the agency was directed to target certain serious criminals for arrest.

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President Trump, who has said undocumented immigrants are bringing crime to the country, signed an executive order that made nearly every undocumented immigrant a priority for removal. Last year, the acting head of ICE, Thomas Homan, said all undocumented immigrants should “be afraid” that agents would be coming for them.

The trend is similar across the country, according to the new data. More than 26,000 “non-criminals” were arrested from October through March — the first six months of the fiscal year — compared with a little more than 13,000 the year before in the U.S.

Though the immigrants in this group did not have convictions, ICE said that more than 16,000 of the 26,000 people had been charged with some type of crime.

Deportations of immigrants arrested by ICE also went up from October through March — from 36,195 individuals to 45,585 in the same time period a year earlier.

Homan has said that because of local and state sanctuary laws that limit cooperation with immigration authorities, officers would have to work harder in California and would be forced to make arrests in communities because of ICE’s inability to pick up many individuals from local jails.

Homan warned that ICE officers would inevitably come across other undocumented immigrants in the course of targeted actions and make what are known as collateral arrests.

“When our officers go out there, it is more often than not that they are encountering more than that individual,” Corey Price, assistant director of ICE’s Enforcement and Removal Operations, which handle immigration arrests and deportations, said Thursday.

Price said that regardless of whether undocumented immigrants have criminal records, they have “violated our immigration laws.”

During a four-day operation at the end of February — which gained wider exposure due to Oakland Mayor Libby Schaaf, who warned immigrants hours before it began — ICE officers traveled from the Central Valley to the northern reaches of California to detain people.

Of the 232 people arrested, ICE said, 115 had prior criminal convictions, including some for violent or sexual offenses. But the agency also said that it “no longer exempts classes or categories of removable aliens from potential enforcement.”

Hamed Aleaziz is a San Francisco Chronicle staff writer. Email: haleaziz@sfchronicle.com Twitter: @haleaziz