ERJ 170/175 flight crew reported a ramp personnel safety issue due to APU inop procedure.

Narrative

Flight was inbound to ZZZ; flight deck Crew conducted a briefing including the steps that would be taken with the inop APU. A radio call was made to Company operations while enroute to ZZZ. ZZZ ops was notified of the aircraft having an inoperative APU; they were told in detail that the aircraft would have engine number two on and that the engine would remain on until ground power was established. Company OPS then let the crew know they understood the message and that they would 'remind the ground personnel'. Upon arriving at the gate; engine one was shutdown while engine two remained on; in order to have a source of power. The flight crew awaited for positive power from the GPU; moments later the crew heard yelling and distress from outside; the Captain asked the First Officer (FO) to look for any abnormalities that may be occuring; but at that point the Captain made the decision as to shut the engine down and have the airplane go 'dark' in the name of safety. Deviation from standard shutdown was deemed necessary in order to protect ramp personnel amongst the commotion. Moments later; after redoing checklists and restoring power via the; now plugged in GPU; the events were better understood. A ramp member had stepped within close proximity of the running engine to place chocks in. No harm to any member had taken place.The cause was the ramp personnel's decision to step within feet from the engine. Flight deck Crew had communicated the status of the airplane when inbound and unfortunately it seems all but one ground member were on the same page.Suggest that when an inoperative APU aircraft is inbound to have thorough briefings on the ground and ensure everyone knows the importance of ensuring the engines are off before approaching critical areas.