Pakistan TV reports said a car laden with explosives had rammed into the FIA building. Some adjacent buildings also were damaged in the explosion.
There have been a number of explosions in Lahore over the past year.
Last December, two bomb blasts at a busy market killed at least 48 people and injured over 100 people. And in May 2009, a bomb blast at a police building killed at least 23 people and injured 200. The nearby offices of the ISI intelligence service were damaged in the blast.