The Republican National Committee’s D.C. headquarters were put on lockdown Wednesday morning after two vials of blood were sent to the building, sources familiar with the matter tell National Review. Staffers were briefly evacuated from the building.

The lockdown was first reported by NBC News. No injuries were reported, and the U.S. Capitol Police’s Hazardous Incident Response Division confirmed to National Review Wednesday morning that they have cleared suspicious package from the premises and the incident will be further investigated.

“Today, vials of blood were sent to RNC Headquarters in DC,” RNC Chairman Michael Whatley said in a statement Wednesday afternoon. “We are thankful to law enforcement, who responded quickly and ensured everyone’s safety. 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.”

This story has been updated.