Labour contractors Abdul Dalim Shaikh and Animesh Biswas were arrested in a case filed under Bharatiya Nyaya Sanhita section 106 (1) related to causing death by negligence. Five labourers entered the water tank and fell unconscious. They were rushed to nearby JJ hospital where four were declared dead on arrival. Police had identified the labourers who died as Hasipal Shaikh (19), Raja Shaikh. (20), Jiaulla Sha Sheikh (36) and Imandu Shaikh, while Purhan Shaikh was hospitalised. The incident occurred on Sunday afternoon at Bismillah Space building on Dimtimkar Road in Nagpada. The two were placed under arrest after our probe found lapses on their part, a police official said. The case is being investigated under section 123 which is about causing harm by administering poison and 3(5) relatedto joint criminal liability, a JJ Marg police station official said, adding that the two were arrested on Monday.