The Immigration and Customs Enforcement (ICE) announced on Thursday that it will send more than 1,600 of its detainees to federal prisons, NPR reports. The move is allegedly a result of the “current surge in illegal border crossings” coupled with the Trump administration’s “zero-tolerance policy.” ICE will use Federal Bureau of Prisons (BOP) facilities as a “temporary measure until ICE can obtain additional long-term contracts for new detention facilities or until the surge in illegal border crossings subsides,” Danielle Bennett, a spokesperson for the agency said in a statement to NPR

Kevin Landy, a former Obama-era ICE official, told Reuters the development is “highly unusual” and added that “a large percentage of ICE detainees have no criminal record and are more vulnerable in a prison setting.” 

One federal facility in Victorville, California is set to house the majority of the detainees, but others will be sent to facilities in Seattle, Washington, La Tuna, Texas, Sheridan, Oregon, and Phoenix, Arizona.  

The news comes as tensions over immigration continue to grow, and Trump’s racist rhetoric fuels more and more ICE raids and arrests. Attorney General Jeff Sessions announced the administration’s a new “zero-tolerance” approach that included the widely criticized policy that separates migrant parents from their children as they enter the country. This policy made headlines when it was reported in connection with the 1,500 unaccompanied migrant children the government says it has “lost.” It is important to separate the two, as the policy of separating children at the border is a new Trump-era policy, and the reason the government has lost track of the children is not entirely connected to that policy. 

A federal judge has sued the Trump administration over this new policy, calling it “brutal, offensive” and arguing it “fails to comport with traditional notions of fair play and decency,” NPR reported on Wednesday. 

The Department of Homeland Security released new data this week that shows an increase in arrests made as people attempt to cross the southern border. Almost 50,000 people were arrested just in the month of May—that’s 160 percent more than the same figure for May 2017.