Nearly 13,000 migrant children are being held in federal shelters, the New York Times reported on Wednesday night, representing more than five times the number of children who were in custody in the spring of last year, 2,400.

Most of the 12,800 children being held in the shelters are unaccompanied minors who crossed into the United States on their own. The influx of these children has placed pressure on resources: Since May, the NYT reports, shelters have been operating at around 90 percent capacity, as opposed to 30 percent last year. That doesn’t leave much room for any unanticipated surges.