SAN JUAN, Puerto Rico (AP) — Three officials with Puerto Rico's Senate were arrested by FBI agents Thursday and later charged by the U.S. territory's federal prosecutor with alleged corruption for a case involving a scheme to defraud the legislature using "ghost employees."

Federal prosecutor Rosa Emilia Rodríguez said 18 charges were brought against Ángel Figueroa Cruz, director of the Senate Office of Government Affair; Isoel Sánchez Santiago, an assistant to the Senate president; and Chrystal Robles Báez, a contractor to the body.

"This kind of practice is not going to be tolerated where federal funds are involved," Rodríguez told a news conference. The case comes as Puerto Rico suffers through an economic recession and continues to recover from devastating hurricanes.

Officials in Puerto Rico and with the FBI say other similar cases are being investigated and did not exclude more people being charged.

The purported scheme involved the accused billing the Senate for professional services that were never provided.

The scandal has shaken Puerto Rico's politicians and officials.

"We are surprised and saddened by the news," Senate president Thomas Rivera Schatz wrote on social media. One of the accused, Sánchez Santiago, was an assistant to Rivera Schatz.

After learning of the arrests, Gov. Ricardo Rossello said his administration "will not tolerate or be an accomplice to any act of corruption wherever it occurs."