Washington (CNN) Immigration authorities have begun conducting raids, a senior administration official said Sunday, in an operation expected to target about 2,000 undocumented immigrants ordered by courts to be removed from the country.

The raids, which will focus on recent arrivals to the country, are slated for Atlanta, Baltimore, Chicago, Denver, Houston, Los Angeles, Miami, New York and San Francisco, a senior immigration official said. New Orleans is also on the list, but the city tweeted last week that US Immigration and Customs Enforcement said it would suspend operations through the weekend in areas hit by Tropical Storm Barry , which weakened to a tropical depression Sunday.

As of early Sunday evening, there weren't any confirmed reports of migrants being apprehended in Baltimore, Chicago or New York, immigrant advocacy groups in those cities told CNN.

"For the most part, it's quiet," Cara Yi, a spokeswoman for the Illinois Coalition for Immigrant and Refugee Rights said. "We've been dispatching rapid response teams out to meet with people who have reported ICE activity over our hotline. None have been confirmed as of yet."

Most of the reports were about sightings of government vehicles, Yi said, but advocates had confirmed they were not ICE.

The American Civil Liberties Union of New York said earlier on Twitter that it had received "some reports of ICE at subway stations, but none have been substantiated."

Acting US Citizenship and Immigration Services director Ken Cuccinelli took issue with referring to the targets of the raids as undocumented.

"They're not undocumented. They've got a court order on a piece of paper -- federal order -- that says they've gotten due process, and (there are) over a million people with removal orders. That's the pool that ICE is drawing from," he told CNN.

ICE will not comment on operational details of the raids, Cuccinelli said, adding that the priority will be apprehending violent criminals and aggravated felons. ICE agents are not "utilizing" allegations of crossing the border illegally, a misdemeanor, as cause for arrest in the raids, he said.

Asked if children would be separated from their parents, Cuccinelli said that information constituted an operational detail. But he did say families are among the 1 million people facing removal orders.

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Immigrants have been hunkering down

News of the raids has left many undocumented immigrants frightened . They've been stocking up on groceries and making plans to stay in their homes with the lights off and the blinds down. Some are staying home from work. Others are posting signs inside their homes reminding them what to do if ICE agents show up. Unsure of where to turn, they're flooding hotlines with calls.

In some cities, local governments and advocacy groups were assisting the immigrants. Supporters in the Chicago neighborhood of Pilsen were posting "know your rights" fliers and encouraging residents to post the fliers, which say, "The family that resides in this home knows their legal rights," at their homes.

Advocates with the Georgia Latino Alliance for Human Rights in Atlanta on Sunday were at a popular Latino shopping center, handing out fliers that read, "ICE free zone."

The fliers also asked immigration authorities to present a signed warrant if they wanted to come inside, adding "This is OUR Constitutional Right!"

Rep. Sheila Jackson Lee of Texas said Sunday that immigration law experts would be on hand at her office in Houston to provide legal resources to individuals looking for information regarding the raids, which she called "draconian."

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In New York City, staff members with the mayor's office of immigrant affairs are also informing immigrants of their legal rights and of city resources that are available in the event they encounter an immigration enforcement official.

"In the face of heartless raids that would tear families apart, we remain steadfast in our commitment to support and defend immigrant communities," Bitta Mostofi, the office's commissioner, said in a statement.

Cuccinelli characterized the raids as normal ICE business and pointed to statistics showing ICE has deported fewer people under President Donald Trump than it did under President Barack Obama.

"This is their job every day. We've got compassionate, loyal ICE agents who are just doing their job," he said. "It shows you how far we've fallen in that it's become news that they would actually go deport people who have removal orders."

Raids were postponed from last month

Mark Morgan, acting commissioner for US Customs and Border Protection who was acting ICE director at the time, said the raids were postponed because operations details had been leaked. Former acting ICE director John Sandweg also expressed concern.

"You never want the target to know you're coming. You want that element of surprise because it keeps you safe," he said. "From an effective perspective, that's why you don't announce these things."

While Trump has repeatedly tweeted about the impending operation, he hasn't jeopardized officer safety, Cuccinelli said, explaining that the situation in June was different than what is happening now.

"The level of detail in the information that came out publicly (last month) was way beyond these general comments the President is making," he said.

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In February, ICE sent around 2,000 letters to families who already had received final orders of removal by judges in absentia, asking them to self-report to ICE offices by March. The upcoming operation is expected to target approximately 2,000 people, the senior immigration official said.

Despite reports of overcrowding at some ICE detention facilities along the southern border, Cuccinelli said ICE has made preparations in anticipation of the raids.

"ICE plans these things superbly," he said.

According to Immigration and Customs Enforcement statistics, 256,085 people were deported in fiscal year 2018, up from 226,119 removals in fiscal year 2017.

Correction: A previous version of this story misstated the nature of the raids. Immigration authorities are expected to begin conducting raids targeting undocumented immigrants.