Gaurav Arora, owner of a photo studio in Gyan Khand area, was admitted to a private hospital, where his condition was said to be critical, police said.
According to the complaint, Arora on hearing a scream last night rushed to the nearby medical store owned by Manish Choudhary and spotted three armed persons attempting to rob the shop owner.
When Arora tried to intervene, one of the armed youths stabbed him in the stomach, a senior police officer said, adding that thereafter the robbers escaped with the looted amount.