A Seattle police officer was arrested Saturday in an ongoing narcotics investigation by SPD, FBI and the Drug Enforcement Administration, and Homeland Security.

The officer was one of four people arrested on drug trafficking charges, according to U.S. Attorney Annette Hayes.

 All four are expected to make their first appearance in U.S. District Court on Monday, when the U.S. Attorney's Office plans to release additional information about the charges. The arrests are a part of an ongoing investigation. 

The officer has been placed on administrative leave without pay.