Two House Oversight Committee leaders are pressing key Trump Cabinet officials for a detailed accounting of the thousands of children separated from their parents since the administration began its “zero tolerance” policy to prosecute every illegal border crossing.

In a bipartisan letter, sent Thursday to Homeland Security Secretary Kirstjen M. Nielsen, Attorney General Jeff Sessions and Health and Human Services Secretary Alex Azar, they make 11 specific requests for information about every single child — including their age, gender, and current location. Since this humanitarian crisis began in April, such details have not been available.

“Like many Americans, we want to ensure that we can reunite children who have been separated from their families as expeditiously as possible,” wrote Rep. Mark Meadows (R-N.C.), chairman of the Government Operations Subcommittee on the Oversight panel and Rep. Elijah E. Cummings (Md.), ranking Democrat on the full Oversight and Government Reform committee.

The lawmakers also want to know the age and gender of the parents of each child, the date the parent was detained and when the child was separated. They also want a full accounting of all the locations the child has been held since families were separated.

Lawmakers have complained about the lack of access to information and the facilities where parents are detained and children are sheltered. Democratic senators sent Nielsen and Azar a similar letter last week asking for weekly updates on the agency’s reunification efforts.

In a call with reporters Thursday morning, Azar said HHS is working “expeditiously” to reunite the fewer than 3,000 children separated from their parents, 100 of whom are under 5 years old.

Azar’s comments came as HHS scrambles to meet a court-appointed deadline to reunite children with their parents being held in Immigration and Customs Enforcement detention centers awaiting trial. Any children already released from HHS care were either sponsored by another family member already living in the United States or deported along with the parent with whom they crossed the border, Azar said.

No children have yet been reunited with a parent who is detained by ICE, but to meet the court order, many will probably be held together in the detention centers. To streamline that process, Azar said parents are being moved to facilities “extremely close” to the shelters where their children are living.

A federal judge in California last week ordered the government to reunify all minor children with their parents within 30 days, and within 14 days for children under 5 years old. Azar said that the agency is working to meet that deadline but that doing so prevents them from its rigorous “standard or even truncated vetting process.” Azar said the agency has deployed additional resources to read through the case files of all the children and attempt to verify parentage, including using DNA tests.

The Office of Refugee Resettlement, housed within HHS, has been responsible for the care of all the children separated from their parents at the border since the inception of the Trump administration’s “zero tolerance” policy. The small agency typically takes in older minors who cross the border illegally on their own and are classified as “unaccompanied alien children.” But for several months, thousands of children in their charge were unwillingly taken from their parents, which medical experts have warned can create long-lasting trauma.

Azar said HHS’s mission is to “protect the welfare of the children with whom we’ve been entrusted.”

“We want this to be as compassionate a process as humanly can be,” he said. “As broken as our immigration system is, we still want to treat people as well as humanly possible going through this difficult process.”