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When the sun goes down, one inmate can't read the labels on his heart medication, he said. Another inmate said he was brought to tears in fear that no one will notice if he suffers an asthma attack.

"I'm scared I won't wake up," the inmate said, according to David Patton, the executive director of the Federal Defenders of New York.

These are just a handful of the stories Patton said he heard on Saturday when he visited Brooklyn's Metropolitan Detention Center.

Located in the neighborhood of Sunset Park, the jail encountered problems after a fire broke out in a gear switch room on Jan. 27, according to the Federal Bureau of Prisons. As a result, inmates inside have become panic-stricken as they wait for the heat and electricity amid dangerously cold weather, according to reports from lawyers and lawmakers.

A woman, who reportedly stormed the main entrance to the Metropolitan Detention Center with others, was pepper sprayed outside the jail in Brooklyn on Feb. 3, 2019. Kathy Willens / AP

"It's disgraceful and it breaks your heart when you talk to people who are frantic and scared and entirely cut off from the outside world," Patton told NBC News on Sunday.

Patton said he and his colleagues will file a lawsuit on Monday spelling out the "unconstitutional conditions" the inmates have been kept in over the past week. Patton said he was unable to go into detail about the suit until after it is filed.

"The big power issue that has caused significant problems this week resulted from the fire on [last] Sunday, but they may have been having other electrical problems before that," Patton said. "The heating problems seem to be independent."

In a statement released on Sunday, the Federal Bureau of Prisons, which oversees the Metropolitan Detention Center, said that power had been restored and staff was working to restore the facility to normal operations.

The bureau also said that new electrical panel was installed on Saturday and that the work on the electrical panel should be finished by Monday. It added that heating to the building was unaffected and inmates have hot water in the showers and in the cells, in addition to access to hygiene items and medical services.

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"We continue to work expeditiously to restore power to the facility as quickly as possible," the statement read.

However, the attorneys who visited the jail described a different scene.

In notes taken during a tour of the jail and shared with NBC News, Deirdre von Dornum, the attorney-in-charge of the Federal Defenders for the Eastern District of New York, described water leaking into inmates' beds from cracks in the ceiling, pitch black cells, and tepid water in the showers.

Hot meals were being served during von Dornum's tour, she wrote, but several inmates showed her cups with "brown or cloudy water from the tap and said it is not drinkable."

She described some inmates not receiving medical treatment for things like bipolar disorder and Crohn's disease.

"These units had a panicky feeling," von Dornum wrote. "One man showed us his infected open leg wound and told us his colitis is so bad that he woke up bloody — and no fresh sheets are available."

That inmate provided von Dornum with medical records that proved he does suffer from colitis and a seizure disorder in addition to having an infected wound.

When Patton toured the prison on Saturday, he said he saw thermometers in several inmates cells showed the temperature ranged between 50 degrees and 69 degrees, with temperatures varying depending on location and proximity to the windows.

The Federal Bureau of Prisons did not immediately respond to a request for comment on the disparity between its account and the attorneys' accounts.

On Sunday night, New York Mayor Bill de Blasio said in a tweet that the power at the detention center was back on. "Thank you to the families, activists and officials who fought for the dignity of people inside. More work ahead—let’s keep at it," the mayor said.

Protesters who stood outside the detention center when the lights came back on celebrated and cheered in support.

Earlier, both New York senator Kirsten Gillibrand and Governor Andrew Cuomo got involved. Gillibrand penned a letter to acting Attorney General Matthew Whitaker asking him to take immediate action and fix the problem and Cuomo asked the U.S. Department of Justice to investigate reports of civil rights violations at the prison.

Patton said his office began having problems contacting inmates during the 35-day government shutdown. He said he's still not sure if some of the issues in the jail stem from the staffing and funding shortages during the shutdown, which may have caused maintenance issues.

He said inmates are able to call their public defenders and attorneys, but have not been able to contact family members.

"They feel like they’re trapped in intolerable conditions and have no idea if anyone out there knows about it," Patton said on Sunday.

Although power is scheduled to be restored on Monday, Patton said the issues of jail conditions reach far past this week.

"We're going to get through this immediate crisis at some point," Patton said. "But I hope people don’t forget about the issues of prison conditions because they're terrible even when power doesn’t go out."