Hundreds were charged Monday in connection with a $14.6 billion health care fraud scheme that supplied millions of opioid pills to drug dealers and saw elderly patients given “unnecessary” wound grafts, the Department of Justice announced.

The operation, which the department called the largest health care fraud takedown in its history, collared 324 defendants, including members of transnational criminal groups and American doctors and pharmacists.

The sick scheme sought to bilk the federal government out of $14.6 billion, with the actual loss to the US government totaling about $2.9 billion, officials said.