Tuesday's blast crushed the external walls surrounding the French compound and was powerful enough to destroy vehicles and shatter windows for several blocks. It occurred before normal office hours, around 7:30 a.m., according to neighbors and witnesses; a later explosion would have resulted in greater casualties, according to Libyan security officials and firefighters who rushed to the scene.
(from the WSJ)
Many Libyans are appalled by this considering what France has done to topple Gaddafi, and unlike Benghazi there are no parts of Tripoli controlled by islamist militia. We don't know at that point if islamists or Gaddafi supporters are to blame.