The State Farm Insurance office on Fairmont at Watters was locked down for hours after a receptionist found a box full of BBs packed inside pill bottles around 10:40am Friday, Pasadena police said.
Bomb squad members were called out to the scene and determined the contents of the package were that of a crudely made explosive device and disarmed it.
Workers who were mowing the lawn Thursday found the package on the property and brought it inside. Police say they don't know who built or left the device there.
The incident is still under investigation.