The US Secret Service is investigating how cocaine was found at the White House, with visitor logs and footage combed for clues. The discovery in the West Wing, which contains the Oval Office and other working areas for presidential aides and staff, led to a brief evacuation. Secret Service agents found the powder in a storage facility routinely used by White House staff and guests to store mobile phones. White House staff are permitted to give tours of some parts of the West Wing to friends and family. Visitors who are not accredited staff must store mobile phones and other personal belongings in cubicles.