A federal judge has ruled that hundreds of immigrant women and children in holding facilities should be released, finding their detention “deplorable” and in grave violation of an earlier court settlement.

U.S. District Judge Dolly Gee said federal authorities had violated key provisions of an 18-year-old court settlement that put restrictions on the detention of immigrant children.

The ruling, released late Friday, is another blow to President Barack Obama’s immigration policies and leaves questions about what the U.S. will do with the large number of children and parents who crossed the border from Latin America last year.

Currently, the Obama administration is detaining an estimated 1,700 parents and children at three detention facilities: two in Texas and one in Pennsylvania.

In her 25-page ruling, Gee blasted federal officials, stating that children had been held in substandard conditions at the two Texas detention centers. She found “widespread and deplorable conditions in the holding cells of Border Patrol stations.” In addition, she wrote that federal officials “failed to meet even the minimal standard” of “safe and sanitary” conditions at temporary holding cells.

“It is astonishing that Defendants have enacted a policy requiring such expensive infrastructure without more evidence to show that it would be compliant with an Agreement that has been in effect for nearly 20 years,” Gee wrote.

Gee gave the government until Aug. 3 to argue why an order she plans to issue should not be implemented within 90 days.

The judge signaled that she planned to enter a nationwide injunction requiring the Department of Homeland Security to come into compliance with a 1997 settlement — known as Flores — that set specific legal requirements for the housing of immigrant children.

DHS plans to respond to the court’s ruling by the Aug. 3 deadline, press secretary Marsha L. Catron said in a prepared statement. It is unclear whether Immigration and Customs Enforcement will appeal the ruling.

“We are disappointed with the court’s decision and are reviewing it in consultation with the Department of Justice,” Catron said.

Last summer, as an unprecedented number of women and children from Latin America were illegally crossing the southwest border, DHS Secretary Jeh Johnson ordered immigration authorities to dramatically expand the number of detention beds for families.

Johnson said at the time that he wanted to send a message that if people came to the U.S. illegally, they would be detained and sent home. In addition, individuals held in detention would be placed in an accelerated docket in immigration courts and could be removed from the country more quickly.

More than 68,000 people were apprehended along the border in fiscal year 2014. They were detained while officials decided whether they had a right to stay. Before the new detention centers for mothers and children were built, many of the apprehended were released with orders to appear at immigration offices throughout the country, because there weren’t appropriate facilities along the border to house families.

Immigrant rights activists and attorneys applauded Gee’s ruling.

Bryan Johnson, an immigration attorney in New York, said Gee’s ruling should extend beyond those still in detention.

“Given the court’s ruling that family detention is unlawful, all of the mothers and children who were removed as a result of family detention should be immediately allowed back into the United States to apply for asylum or special immigrant juvenile status,” he said.

Ira Mehlman, a spokesman for the Federation for American Immigration Reform, a Washington, D.C.-based group opposed to illegal immigration, said Gee’s decision sends a “dangerous message.”

“The number of kids that are going to be enticed from this ruling to come from Central America and risk their lives and subject themselves to injury or rape to cross Mexico is going to rise,” Mehlman said.

Many of the Latin American families and children who crossed the southwest border illegally last summer were fleeing crushing poverty and escalating gang violence. The exodus also was partly fueled by rumors in their home countries that unaccompanied children and single parents with at least one child would be allowed to stay.

Some people who crossed were apprehended, while others surrendered to Border Patrol officials and requested asylum, which is within their rights under U.S. and international laws.

In response, the Obama administration expanded detention centers for families, and the court system — already grappling with a backlog of cases — became even more bogged down. Hundreds of immigrants have been ordered removed, some have been released. Mothers and children are still detained at two Texas facilities: one in Dilley, another in Karnes City, which are both run by private companies under contract with ICE. A third, in Berks County, Pa., is run by the county.

The Flores vs. Meese settlement requires the U.S. to release immigrant children or house them in the “least restrictive environment” possible. A juvenile immigrant cannot be detained for more than an estimated 72 hours unless they are a significant flight risk or a danger to themselves or others. The children must be released to a parent or legal guardian.

One of the arguments federal officials made was that the settlement did not apply to children who were accompanied by parents. Gee disagreed.

In April, the judge issued a preliminary ruling, signaling that she would find in favor of the plaintiffs that it was inappropriate to hold a parent and child unless there was a flight or safety risk.

Gee asked both sides to negotiate a revised agreement before her final ruling. After six weeks of negotiations, they had failed to reach a deal.

Leon Fresco, a Justice Department deputy assistant attorney general, had warned Gee that if her ruling stood, it would encourage the Obama administration to separate parents and children, turning them into “de facto unaccompanied children.”

Peter Schey and Carlos Holguin, who launched the lawsuit against federal officials and have served as court-appointed lawyers for all immigrant children in federal custody since the 1997 settlement, said the ruling marks the beginning of the end of family detention.

“We’re hopeful this decision will be among the final straws ending a misguided, mindless policy of incarcerating women and children in violation of the Flores settlement, international law and all of what most of us hold decent,” Holguin said.

Gee’s ruling comes amid a resurgence of the debate on immigration following Republican presidential candidate Donald Trump’s characterization of Mexican immigrants as drug dealers and rapists. Just a few weeks later, the issue was again pushed to the forefront after the suspect in the killing of a woman on San Francisco’s waterfront turned out to be a Mexican national with a history of drug convictions who had repeatedly been deported.

Her ruling also comes about a month after federal officials announced a new policy that would allow hundreds of immigrant women and children to go free on bond if they could prove they were eligible for asylum or another type of immigration relief. But immigrant rights activists continue to argue that mothers and children should not be held at detention facilities at all.

Los Angeles Times staff writer Molly Hennessy-Fiske and Brian Bennett of the Tribune Washington Bureau contributed to this report.