Updated

Police, the FBI and state attorney general's investigators served warrants Monday at six southern Nevada medical clinics associated with a facility accused of infecting patients with hepatitis by reusing syringes and vials of medicine.

Police say the raids are part of a criminal investigation of officials at the Gastroenterology Center of Nevada.

The clinic has four offices in Las Vegas, one in Henderson and one in North Las Vegas.

The investigation was triggered by a hepatitis C outbreak that health officials blame on unsafe practices at a southern Nevada clinic from 2004 to this year.

Six patients at the Endoscopy Center of Nevada have been found to be infected with the potentially fatal virus. Another 40,000 are being notified to get tested.