Puerto Rico ? U.S. federal agents arrested dozens of doctors accused of obtaining medical licenses through fraud or bribery, carrying out sweeping raids Thursday across Puerto Rico.

A federal grand jury indicted 88 doctors following an investigation into members of the U.S. Caribbean territory’s medical licensing board, who allegedly altered low-scoring tests to certify unqualified candidates.

The doctors – mostly Puerto Ricans who studied medicine in the Dominican Republic, Mexico or Cuba – paid board members bribes of as much as $10,000, according to the indictment. At least 75 were practicing medicine in Puerto Rico, including some at hospitals or emergency rooms, authorities said.

The arrests began near dawn. Some suspects – including Pablo Valentin, a former executive director of the licensing board – were seen on television being led away by local police and agents of the U.S. Food and Drug Administration.

Most of the suspects failed the licensing exam multiple times.