Three workers died of suffocation at Parry's Sugar Industry near Sankili village in Regidi Amadalavalasa Mandal in Srikakulam district on Friday, police said.
As the sugar factory was to be closed at the season's end, these workers were cleaning the cooling tower.
Yerneni Chandra Rao (45) first cried out for help saying he was suffocating after climbing into the cooling tower.
Kemburu Sombabu (42) and Lakshmu tried to help him, but they too suffocated and died on the spot.
All three belonged to Adavaram village in Regidi Amadalavalasa Mandal.
Police have registered a case of negligence and further probe is on.