The Trump administration abruptly changed its program for granting medical deferral requests to undocumented immigrants this month, sending letters to several families rejecting their requests.

The letters from the U.S. Citizenship and Immigration Services agency informed families that USCIS would no longer consider their requests for medical deferral, which protected seriously ill undocumented immigrants from deportation while undergoing treatment in the U.S.

The letters warned that the families will be deported if they don’t leave the country within 33 days.

A USCIS spokesperson told TPM via email that the Immigrations and Customs Enforcement agency is now overseeing the requests, effective August 7.

“Deferred action does not provide lawful immigration status, and it does not excuse any periods of unlawful presence before or after the deferred action period,” the spokesperson said. “Deferred action can be terminated at any time at the agency’s discretion.”

However, the letters to families did not inform them of that change, and it’s not clear that ICE will accept deferral requests at the same rate. Several requests from families with sick kids have already been denied after the new policy was enacted.

The medical deferred action program allowed undocumented immigrants with severe illness such as cancer and HIV to stay in the U.S. for two years. Many of the program’s beneficiaries are children, several of whom come from countries with inadequate health care services.