While those present on the spot claimed that the deceased, identified as Ashok Kumar Sharma (34), died after being electrocuted, initial investigations indicated it was a case of natural death.
The incident took place around 5:45 am when Sharma reached the bus depot, marked his duty and proceeded toward the bus. It was raining and there were puddles in the area. A while later, he was found lying unconscious in a puddle.
"A PCR call was made and a police team rushed to the spot which took him to a nearby hospital where he was declared brought dead," said a police official.
However, doctors who first attended Sharma at the hospital said that it looked that he was not electrocuted.
"It seems that he either suffered a heart attack or suffered head injury after slipping of the puddle. We are waiting for the postmortem report to determine the cause of death. Although no case has been registered in this connection, we are inquiring the matter under section 176 CrPC," the official said.
The Millennium Bus Depot, situated in south-east Delhi, is one of the largest bus depots in the world.