The buses have been arriving from Texas and Arizona for months, after the Republican governors of those states started offering "voluntary" bus trips to the nation's capital for migrants caught crossing the border from Mexico.

"We were told we were going to be helped here, that somebody was waiting for us," Andres David Blanco, who left Venezuela a month and a half ago, said in Spanish after he arrived at Union Station on Tuesday night.

A network of mutual aid organizations armed with limited resources, and a nonprofit operating with a federal grant have been scrambling to help migrants, while the number of buses arriving in the city continues to rise.

That patchwork of aid fell short Tuesday night, after core organizers and volunteers with the Migrant Solidarity Mutual Aid Network advocates were in quarantine after being exposed to the coronavirus while helping migrants over the weekend.