The Republican National Committee (RNC) headquarters went on a complete lockdown, with staff forced to evacuate, after what appeared to be a biological weapon was delivered to the building.

According to Breitbart News, an anonymous individual sent a package containing vials of blood to the RNC headquarters, causing chaos in the building. The package, which RNC Chairman Michael Whatley had described as a “biological attack,” was addressed to former President Donald Trump.

It’s not clear when the package was delivered to the RNC building. Reports, however, showed that the package was discovered in the building on Wednesday. Law enforcement officers responded to the building, with RNC staff forced to exit the building and wait outside for about an hour before they were allowed into the building.

While the dangers posed by the package remain unclear, a hazmat unit —a team that investigates bio-weapon incidents— was called to the headquarters.

A source familiar with the incident also confirmed to the AP News that the package had the former president’s name on it. The source spoke under anonymity because they were not authorized to speak publicly on the matter. The sources did not say if there was any other message attached to the package.

Whatley, in an email to RNC staff, blasted the attack, adding that it was a clear effort to stop the RNC’s bid to get Donald Trump elected in November.

“Today, vials of blood were sent to RNC Headquarters in DC. We are thankful to law enforcement, who responded quickly and ensured everyone’s safety,” Whatley said in a statement after the building was deemed safe. “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 revolting attack comes on the heels of pro-Hamas protestors violently demonstrating on college campuses and deranged Biden supporters physically attacking our campaign volunteers for supporting President Trump.”

Capitol Police confirmed the incident in an X post, revealing that the case was being investigated.

“This morning, we responded to the 300 block of First Street, SE, for the report of a suspicious package,” the post reads. “The package was cleared by our Hazardous Incident Response Division. It contained two vials of blood. The source of the package & its contents will be further investigated.”