Apparently frustrated by his failure to rob a man who was headed to work Monday, an aspiring Duboce Triangle mugger discharged his firearm — but no one was injured, except, perhaps, the failed criminal's pride.

According to the San Francisco Police Department, a 61-year-old man was carrying a briefcase as he headed to work at 9:05 Monday morning, walking on the 200 block of Noe Street between 15th and 16th Streets.

Suddenly, a man in his 20s approached, demanding that the older man hand over the briefcase. But try though the criminal might, the older man "refused to let go of the case," police say.

In an apparent effort to intimidate his victim, the mugger "produced a weapon and fired one shot into the air," but to no avail. Thwarted and empty-handed, the suspect fled the scene by car, and hasn't been seen since.

Police say that the briefcase-holding man was not injured in the incident, and did not suffer any losses in the confrontation. The suspect remains at large, and no arrests have been made in the case.