Maryland Attorney General Brian Frosh announced Thursday he will join a lawsuit against the Trump administration, seeking to reunite more than 2,000 children who have been separated from their parents after crossing the southern border.

Frosh joins more than 10 other states — including Pennsylvania, Massachusetts and California — in the suit, which demands that the Trump administration stop separating immigrant families after they cross the border and reunite the ones that have already been separated, according to NBC News.

The action is being led by Washington state’s Attorney General Bob Ferguson. The suit will be filed in court Tuesday, according to the Baltimore Sun.

“It’s a disgrace for the United States of America to engage in this kind of conduct,” Frosh told the Sun Thursday. “It hurts the most vulnerable people in the world, little children, and the harm is going to be in many cases irreparable.”

The legal action comes on the heels of a “zero tolerance” immigration policy, announced in April by U.S. Attorney General Jeff Sessions. The policy directs prosecutors to take up all cases of illegal entry referred to them by the Department of Homeland Security. As part of the policy, children are separated from their parents and placed in holding facilities across the country by the Department of Health and Human Services’ Office of Refugee Resettlement.

“If you smuggle illegal aliens across our border, then we will prosecute you. If you are smuggling a child, then we will prosecute you and that child will be separated from you as required by law,” Sessions said in May. “If you don’t like that, then don’t smuggle children over our border.”

Trump signed an executive order Wednesday that said he would end the policy, but there are few details on how the administration will reunite the families who have been separated.

In his announcement of the lawsuit, Ferguson argued that the order was “riddled with so many caveats as to be meaningless.”

The lawsuit will allege that the Trump administration’s zero tolerance policy is “irrationally discriminatory” and violates the due process rights of the parents and children, in addition to demanding that Trump’s executive order be updated to include a clear plan for family reunification.

Maryland is one of 17 states that have received some of the 2,300 separated children. The Sun reported on Wednesday that “dozens of children” from El Salvador, Honduras and Guatemala one as young as 18 months old have been placed in foster homes in Anne Arundel County and others in dormitories in Anne Arundel and Baltimore counties.

On Wednesday, Frosh sent a letter to the secretaries of Health and Human Services and Homeland Security departments requesting the identity, location and age of children sent to Maryland as well as the identity of their parents and a plan for reunification.

At a Greater Baltimore Committee event Thursday, Frosh expressed concern about growing animosity towards immigrants.

“This has been a period in which we have seen hatred on the rise and internal strife and division unlike anything I have seen in my adult life,” he said, “with the possible exception of maybe the 1960s, when we were in the middle of a struggle for civil rights and in the middle of the Vietnam War.”

The backlash against the Trump administration’s policy has been swift, with legislators from both parties condemning their actions and calling for immediate reversal. Maryland Gov. Larry Hogan joined several governors across the country in recalling National Guard members deployed to the southern border.

“The Trump Administration’s actions endanger the safety and well-being of innocent children,” Frosh said in a statement Wednesday. “Our concerns about the utter lack of accountability and failure to plan for reunification of these families must be addressed with urgency.”