The practice has been going on for about a month, according to the Border Patrol’s Tucson sector, which covers most of Arizona’s border with Mexico.

It was a central topic of a meeting Border Patrol officials in Tucson held Friday with local law-enforcement, elected and community leaders.

The number of migrant families released in Tucson has surpassed the ability of local nonprofits to house them. This past week, the city of Tucson and Pima County opened temporary overflow shelters to house migrants, although those shelters are once again empty, at least for now.