© Agence France-Presse / Jewel SamadBomb squad officers were dispatched after the two "crude" bombs were located inside a Borders store
Two small bombs partially detonated in a bookstore in Denver, Colorado early Saturday causing minor damage but no injuries, the Federal Bureau of Investigation said.

Bomb squad officers were dispatched along with police and FBI agents after the two "crude" bombs were located inside the Borders store, which had been broken into in the Colorado Mills Mall in Lakewood, Colorado.

"The two small crude devices partially functioned in a nominal manner causing no damage to the Mall and only minimal damage to a small area of the interior of the Borders Bookstore," said an FBI statement.

"No injuries were reported and no threats have been communicated to Borders Bookstore or the Mall," it added, saying the mall was open for business although police were still working in the area where the blasts occurred.

Borders, until recently the second-largest US bookstore chain, filed for bankruptcy in February, announcing the closure of 30 percent of its over 640 stores in the United States.

The chain, which had 6,100 full-time and 11,400 part-time employees before the closure announcements, has lost millions of dollars in recent years as the book industry faces online competition and transitions to digital products.