Robbing someone is, without exception, a terrible idea. Robbing someone in broad daylight one block from police headquarters? About as dumb as ideas get.

That seems what happened this morning in the 1200 block of South Lamar Street:

Shooting appears to have involved an off-duty @dallaspd officer. Officer is ok. One person transported. One person deceased.

— Lt. Max Geron (@MaxDPD) April 4, 2014

Police have identified the officer as Sergeant Jackie Moore, a 15-year veteran of the department. At about 9:30 a.m., she was across the street in uniform when she heard a woman screaming for help from the business located at 1220 South Lamar.

The officer discovered a knife-wielding man trying to stab an employee of the business. According to witnesses, the man had been discovered trespassing in a fenced-in area of the property and was being escorted to the street when he attacked. When she saw that the employee was in danger, she fired.

The suspect was pronounced dead at the scene. The man he attacked was taken to Baylor Hospital. A second employee -- the woman who screamed -- was uninjured.

So, potential criminals, let this incident serve as a reminder:

@MaxDPD @DallasPD off the clock....always on duty.

— Alex Garcia (@Alex1DPD) April 4, 2014

This post has been updated with additional information from police.

Send your story tips to the author, Eric Nicholson.

• Crime