The Northern Colorado Bomb Squad neutralized the device. Fort Collins police said the device appeared to be homemade.
Police said no one was injured. An investigation is underway.
Anyone with information about the crime is asked to contact Fort Collins Police at 970-221-6540 or Crimestoppers of Larimer County at 970-221-6868.
Tipsters can remain anonymous and may be eligible for a cash reward.
(KUSA-TV © 2012 Multimedia Holdings Corporation)