A TTD-owned free bus caught fire midway while motoring up to Tirumala here on Saturday.
The mishap took place on the second ghat road about a kilometre ahead of reaching the town.
The driver who noticed a thick smoke emerging from the engine immediately halted the bus and evacuated all the Srivari Sevaks on board.
Amid conflicting reports, it is not immediately known as to what exactly triggered the mishap.
