They were in the U.S. on the OPT visa which allows for a short period of work after graduation: Indian students make up 50% of cases in US visa crackdown – Investing Abroad News | The Financial Express
But 50% of the “students” had already graduated from their university programs. The crackdown on international student visas has not been adequately explained by any government official. No one seems to know, in most cases, why this is happening although there is this item:
While 86 percent reported some level of interaction with the police, 33 percent had their case dismissed, were never charged, or were never prosecuted.
A lot of it seems to be based on erroneous information.