Sunday’s reception at the Washington Hilton hotel was not adequately secured. The event was the site of the shooting, according to White House sources, The Washington Post reports.

The newspaper notes that events attended by the US president and cabinet members are usually classified as special events and receive the corresponding security clearance. However, the Washington Hilton event was not given the status that would allow for the full use of federal resources,.

The  sources say that security at the reception was weaker than at other high-ranking officials’ meetings. This, in essence, left the US in an extremely vulnerable position.