WASHINGTON – The US Secret Service is investigating a “small amount” of a “white powdery substance” discovered in a “West Wing work area” on Sunday, a Secret Service official said.

The substance, which tested positive for cocaine in a preliminary field test, according to a source familiar with the investigation, prompted a brief evacuation inside the White House on Sunday night. The source added that the substance was found in a small bag about the size of a dime.

The Secret Service is testing the substance, which they determined was not «hazardous,» and said in a statement that they are looking into the matter.

Secret Service police outside the White House on Tuesday.Tasos Katopodis/Getty Images

«On Sunday night, the White House complex went into lockdown as officers from the Uniformed Division of the Secret Service investigated an unknown item found within a work area,» said Anthony Guglielmi, a spokesman for the Secret Service. «The DC Fire Department was called in for evaluation and quickly determined that the item was not dangerous. The item was sent for further evaluation and an investigation is pending into its cause and how it entered the White House.»

President Joe Biden was not in the White House at the time the substance was discovered; he left for Camp David on Friday and returned to Washington on Tuesday morning.

A source familiar with the investigation said USSS will conduct a full review, which will include consulting cameras and entry logs to determine who had access to the space where the small plastic bag was found Sunday night.

While the investigation will try to determine who is responsible for the item, the source acknowledged that it could be difficult given the number of people passing through the area and it is unknown how long the bag was there. The substance was found in a common space where employees and visitors can store phones and personal items that are not taken to other parts of the West Wing.

The source added that they are not expecting any surprises as to what the substance is after the field test result indicated cocaine, but proper laboratory tests are underway for a formal conclusion.

The White House declined to comment.

Peter Alexander contributed.