The Republican National Committee logo is shown on the stage as crew members work at the North Charleston Coliseum, Jan. 13, 2016, in North Charleston, S.C.

Rainier Ehrhardt/AP

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Rainier Ehrhardt/AP

The Republican National Committee logo is shown on the stage as crew members work at the North Charleston Coliseum, Jan. 13, 2016, in North Charleston, S.C.

Rainier Ehrhardt/AP

The Republican National Committee said its headquarters in Washington, D.C., were placed under lockdown Wednesday morning after vials of blood were sent to the building.

In a statement, the RNC referred to the incident as a “biological attack.”

“We are thankful to law enforcement, who responded quickly and ensured everyone’s safety,” RNC Chair Michael Whatley said in the statement. “The lockdown has been cleared and staff has resumed their office duties because we remain unintimidated and undeterred in our efforts to elect President Trump to the White House.”

The office was cordoned off for a couple hours as United States Capitol Police responded to the report of a suspicious package.

The package, which contained two vials of blood, was cleared by the department’s Hazardous Incident Response Division, according to the USCP.

The source of the package and its contents will be further investigated, according to the USCP, which gave an all-clear later in the morning.