The man, Raghuram Iyer, was shot at outside Green View Society. Two unidentified men snatched his chain but when he protested, they shot at him, police said.
They fled after taking his chain and attacking him.
He sustained injuries to his shoulder and is currently undergoing treatment at a hospital where his condition is critical, they added.
The incident has been captured on CCTV cameras installed near the housing society and their footage is being analysed to identify the accused.