DETROIT -- The arrests of dozens of Iraqi Christians in southeastern Michigan by U.S. immigration officials appear to be among the first roundups of people from Iraq who have long faced deportation, underscoring rising concerns in other immigrant communities.

U.S. Immigration and Customs Enforcement officials on Monday declined to say how many were taken into custody, but advocates say at least 40 people were arrested near or at homes, mostly on Sunday. Roughly 100 people protested Sunday at a Detroit detention center, many expressing their concern for the arrestees' safety.

Chaldeans are among Iraqi Christian denominations that emerged in the faith's early days, and many speak languages similar to those spoken at the time of Christ. Their population in Iraq has dwindled as hundreds of thousands have fled war and violence over the decades.

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Hundreds of people gathered in Sterling Heights to protest the arrests. Marvin Yousef was one of the demonstrators, CBS Detroit reports. "They're targets. If they go back to Iraq, they're going to kill them," Yousef said.

ICE said in a statement released Monday that all of those arrested had criminal convictions, including for murder, rape, assault, burglary, weapons violations and drug trafficking, and were ordered deported by an immigration judge after "full and fair" proceedings.

Immigration officials said the judge determined they were "ineligible for any form of relief under U.S. law," but declined to discuss the appeal process or other legal options. Most of the orders had been issued a while ago but ICE could not remove them until an agreement was reached with Iraq.

Nathan Kalasho, who runs a Detroit academy that educates Iraqi Christian students, called some of the convictions "petty."

"Some of them were nonviolent, and some of these were 30 or 40 years ago," he told CBS Detroit. "These people have paid their debt back to society; they contribute to the workforce, countless hours."

The Homeland Security Department has boasted in recent months that Iraq has agreed to start allowing the return of immigrants who have been ordered out of the United States. The first details of that agreement came amid litigation over President Trump's travel ban, and the first version of the order included seven countries.

A subsequent version of that order, intended to quell legal challenges, dropped Iraq from the list of countries whose citizens were banned. The travel ban remains on hold amid legal challenges.

The arrests come amid broader, aggressive immigration policies by the Trump administration. Immigrants who already have deportation orders and were allowed to stay in the country under the prior administration have become a target under Mr. Trump, with some getting arrested on the spot during check-ins with officers. Such arrests have dismayed family members and sent chills through immigrant communities.

ICE said the Detroit-area arrests were part of its efforts to deal with a case backlog, and the vast majority of those arrested were being detained at a facility in Youngstown, Ohio. Officials said they don't confirm specific deportation plans.

Chaldean American educational and community leader Nathan Kalasho, whose family operates a Detroit-area charter school for Chaldeans and others from Iraq and Syria, said the deportations are the result of a "back-door deal" between the U.S. and Iraq.

"Who could think that this deal could possibly be good?" said Kalasho, who added it's particularly concerning after Chaldeans and other Iraqi Christians have been designated victims of genocide. "Iraq assumes a few hundred former nationals - some of these people have spent nearly their entire lives here and some have committed minor offenses. They've paid their debt to society."

Judy Rabinovitz, deputy director of the American Civil Liberties Union's Immigrants' Rights Project, said the removal orders, while legal, could be decades old and don't reflect changing conditions in the countries of origin. She said similar removals have been carried out for Somalia and Cambodia natives.

"Anyone with a final order is basically vulnerable at this point," she said. "The problem is, these aren't cases where these are people who pose a risk to public safety - it's just sort of irrational, low-hanging fruit. Get the numbers, get people out."