Senior officials of the Delhi Fire Services said that they have made comprehensive arrangements for the summit which also includes setting up a control room at Pragati Maidan.
The godown was being used to store chemicals like paraffin that are utilised in PVC manufacturing.
According to fire officials, information about the blaze was received at 4.07 am, following which 21 fire tenders were rushed to the spot.
The fire was at the endoscopy room, located above the emergency ward, on the second floor of the Old OPD. All patients in the room have been evacuated, AIIMS sources said.