(CNN) Many inmates at the federal detention center in the New York borough of Brooklyn were still sitting in their cold and dark cells Saturday because of a partial power outage, the director of Federal Defenders of New York David Patton and a representative for the union representing the facility's workers said.

Federal officials said work to fix the power situation at the Metropolitan Detention Center will not be finished until Monday.

One US representative who visited the facility Saturday told CNN affiliate WPIX that the temperature was as low as 49 degrees in the detention center.

"The heat is sporadic and it's uneven," Nydia Velázquez told the station.

It's been a trying situation for more than a day, Patton said.

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