Police said the deceased have been identified as Manjunathan (30) and Sankaran (32), both the driver and cleaner of the Eicher truck that was ferrying fruits and vegetables from Andhra Pradesh to Chennai.
The two others were Krishnappa (65) and Somasekharan (31), both travelling in the KSRTC bus.
Thirty-five passengers of the bus, who were injured in the accident, were rushed to Government Headquarters Hospital at Walajapet and private hospitals here for treatment.
The condition of three persons was stated to be critical.
The KSRTC bus was returning to Kolar in Karnataka after a pilgrimage to Sri Aadhiparasakthi Temple at Melmaruvathur.