President Donald Trump used wartime authority to deport nearly 240 alleged Latin American gang members to a mega-prison in El Salvador over the weekend. A federal judge unsuccessfully sought to block the administration’s actions,

Tren de Aragua, a gang born out of a Venezuelan prison, is a loose network that doesn’t operate like groups typically considered terrorist organizations.

The deportation of 261 Venezuelans, including suspected members of the gang, was carried out on Saturday. By the time a federal court halted the move, two planes carrying immigrants had already left the country.