WASHINGTON (NewsNation) — An investigation is underway after a suspicious substance sent to the Republican National Committee (RNC) headquarters in Washington, D.C., prompted a temporary lockdown and evacuation Wednesday.

The suspicious package was left on the steps of the RNC headquarters and contained two vials of blood, U.S. Capitol Police confirmed to NewsNation.

The Associated Press reported the package was addressed to former President Donald Trump following the presumptive presidential nominee’s takeover of the national party apparatus.

It was unclear if any message accompanied the vials explaining why they were sent.

The hazardous incident response division was called in to clear the package and the contents will be further investigated, authorities added. It remained unclear whether anyone came into contact with the blood and to whom it belonged.

D.C. Metro Police and D.C. Fire and Emergency Management Services confirmed their departments both assisted Capitol Police.

Rep. Richard Hudson, R-N.C., who serves as the chair of the National Republican Congressional Committee, told reporters Wednesday he was informed the building has since been cleared.

“A suspicious package was delivered, out of an abundance of caution and following protocol, we called in a hazmat team. I say we … they (RNC officials) called in a hazmat team,” Hudson told The Hill.

It was not immediately clear whether authorities had identified a suspect or taken anyone in custody.

The Associated Press and The Hill contributed to this report.