A federal judge said the Trump administration is “at fault” for losing track of more than 400 migrant parents deported while their children remained in U.S. custody.

U.S. District Judge Dana Sabraw credited the administration for taking steps to reunify more than 1,800 children separated from their families at the border by Thursday’s deadline. However, Sabraw turned his attention to the 431 children still in custody after their parents have been deported.

"The government is at fault for losing several hundred parents in the process and that's where we go next," the judge said, according to CBS News.

The judge ordered the government and the ACLU, who is representing these parents, to submit written updates every Thursday on the process of reunification.

As of Thursday, 711 children remained in U.S. custody because their parents or guardians are ineligible for reunification, including the 431 children whose parents have been deported.