GSA Administrator Martha Johnson, Public Buildings Service chief Robert A. Peck and Johnson's adviser Stephen Leeds are out as of today, the paper said.
Their exits come as the agency, which is responsible for handling the business operations of the US federal government, is drawing criticism for spending $835,000 on an employee event in Las Vegas in October 2010.
Among their expenses for the gathering: $3,200 for a mind reader, $6,300 for a commemorative coin set display and $75,000 for a training exercise aimed at building a bicycle, the Washington Post said.
The spending is the subject of an upcoming report from the agency's internal investigator.
It isn't yet clear what the GSA was discussing at its internal conference, but the Washington Post said 300 employees were in attendance and that a clown and a comedian were also present.
In her formal resignation letter submitted to the White House and posted online by the Washington Post, Johnson said the agency "made a significant mis-step."