A new report criticizes the handling of an explosive device found outside a Detroit federal building and kept inside for three weeks before authorities were alerted.

The Detroit News said Wednesday that the report by the U.S. Homeland Security Department also faults the training, hiring practices and oversight of security guards at the McNamara Federal Building. That's where a tool bag with explosive components was left on Feb. 26, 2011, and not identified until March 18.

The report says the device didn't explode but represented a serious safety risk. It says three guards were fired, a fourth resigned and five others were suspended for their involvement.

Homeland Security Undersecretary Rand Beers writes that the department has since issued standardized national guidance on how to deal with unattended suspicious packages.