The man, Ramesh, was beaten up allegedly by a mob near Mangolpuri railway station between 2:30 and 2:45 am.
According to the woman's complaint, two men came on a scooter and one of them snatched her mobile phone outside her shanty. When she tried to catch them, two of their accomplices came and started beating her. When she raised an alarm one of them took out a knife and tried to stab her. Meanwhile, locals gathered and caught one of them while three others managed to escape, a senior police official said.
The man who was caught was identified as Sultanpuri resident Ramesh. He was thrashed by the angry mob, the official said, adding, that the woman claimed that she tried to stop the people from beating the man, but they did not pay heed to her request.
The man was later rescued by the police and rushed to a hospital, the police said.
Two separate cases have been registered in connection with the robbery attempt and another with the man's death, they said.
Postmortem will confirm the exact reason of his death, they said.
A senior police officer will conduct inquiry into the matter and submit a report in this regard at the earliest, the police added.