A federal judge’s order blocking ICE agents from arresting illegal immigrants in or around Massachusetts courthouses sent shock waves through the enforcement ranks.

“I can’t believe it,” one immigration official told the Herald.

U.S. District Judge Indira Talwani, an Obama appointee, issued her preliminary injunction Thursday banning Immigration and Customs Enforcement officers from any “civil immigration actions inside courthouses.”

Talwani’s injunction gives Suffolk District Attorney Rachael Rollins and Middlesex District Attorney Marian Ryan a big victory. They filed a federal lawsuit in April seeking to boot immigration officers from district courts, arguing that ICE’s practice of intercepting criminal defendants who are illegal immigrants could have a chilling effect on migrant communities’ involvement with the law.

The Boston-based federal judge’s order states that ICE agents cannot civilly arrest “parties, witnesses, and others attending Massachusetts courthouses on official business while they are going to, attending, or leaving the courthouse.”

The judge is allowing ICE agents to seize “individuals brought to the courthouse in state or federal custody.”

“I’m thrilled,” Rollins said of the injunction. “We look forward to continuing our vital work in courthouses across Suffolk County that will be positively impacted by (the) ruling.”

Ryan also praised the judge’s move, saying the “federal court has recognized the irreparable harm being caused by ICE’s disruptive policy of using our courthouses to conduct civil arrests.”

But Jessica Vaughan, a national immigration expert with the Center for Immigration Studies, said the ruling places ICE agents in danger.

“ICE agents have the authority to make these arrests, and they need to do it in the courts because it’s safer that way for officers. The judge is giving into the politics of this issue,” Vaughan said.

“It’s an absurd ruling,” she added. “The judge should be examining the DAs’ demands in respect to the Constitution.”

The DAs filed their lawsuit days after Newton District Court Judge Shelley Richmond Joseph and a court officer were indicted on federal obstruction charges, accused of allowing an illegal immigrant to bolt out a basement door at the court to elude ICE agents last year. The illegal immigrant was in court on drug charges out of Newton and had been deported twice before.

U.S. Rep. Ayanna Pressley (D-Boston) said the decision “affirms the dignity and humanity of our immigrant brothers and sisters in the 7th (Congressional District) and throughout our country.” She added everyone “has a right to feel safe and secure.”

An ICE spokesman said the agency is reviewing the decision and ‘‘respects the ruling of the court.’’

The judge, in a 29-page memorandum on her decision, adds the DAs “have demonstrated a likelihood of success on the merits.”

She added, “Criminal defendants will be unable to vindicate their rights if they are taken into ICE custody prior to appearing in court or if witnesses in their defense are too fearful to visit a courthouse.

“None of these harms can be remedied after the conclusion of this litigation,” Talwani wrote. “Therefore, the court finds that the Plaintiffs have alleged irreparable harm sufficient to warrant an injunction.”