About 300 people have been released from immigration detention centers in Arizona since Thursday, when the federal government started to review each case in anticipation of widespread budget cuts.

"As fiscal uncertainty remains over the continuing resolution and possible sequestration, ICE has reviewed its detained population to ensure detention levels stay within ICE's current budget," said agency spokeswoman Amber Cargile.

All of them remain in deportation proceedings, she said. About 2,280 people remain in immigration detention in Arizona.

The move took many by surprise, and not everyone was happy to hear about it.

Gov. Jan Brewer said in a news release she was "appalled." "This is pure political posturing and the height of absurdity given that the releases are being granted before the federal 'sequestration' cuts have even gone into effect," she said.

Arizona Sen. Jeff Flake called it a "deeply misguided move by DHS."

"With more than $1 trillion in budget deficits, there are many opportunities to rein in federal spending. Releasing hundreds of detainers who have violated the law is most certainly not one of them," he said in a written statement.

Pinal County Sheriff Paul Babeu said there was "a mass release" in his county. "ICE agents were paid overtime Saturday and Sunday to release over 500 detainees in Pinal County alone," he said in a news release.

All of the five immigration detention centers in Arizona are in the county, including the Pinal County Adult Detention Center, operated by the Sheriff's Office.

Babeu's numbers come from ICE supervisors in Arizona who called him directly, said Tim Gaffney, spokesman for the Sheriff's Office.

"Neither law enforcement nor any of our citizens were notified of this decision until over a dozen ICE employees and supervisors notified Sheriff Babeu privately," he wrote in an email.

It costs ICE about $164 per day per detainee at a capacity of 32,800 detention beds nationwide, according to the National Immigration Forum, an organization that advocates for immigrants.

Gaffney said the rate at the Pinal County Adult Detention Center is nearly $60 per day per detainee.

Details on who exactly is being released were not provided, but Cargile said, "Priority for detention remains on serious criminal offenders and other individuals who pose a significant threat to public safety."

Caroline Isaacs, local program director for the American Friends Service Committee, said, "To me, it's simply a more honest revelation of the fact that most of the people in detention don't need to be there in the first place." The committee is a national non-profit social justice organization.

"Eighty percent of prosecutions in the federal judicial system are for crossing the border and crossing the border again," she said.

Contact reporter Perla Trevizo at ptrevizo@azstarnet.com or at 573-4213. On Twitter: @Perla_Trevizo.