The victims, who hailed from Bihar, took ill after consuming meals in their room in Ganaur sub-division of Sonepat yesterday.
When another farm labourer Dinesh Paswan arrived at the scene, he raised an alarm following which locals rushed the labourers to PGIMS at Rohtak where three of them died.
The victims were identified as Dinesh Pal (25), Babloo Paswan (18) and Guttan alias Gatar (25). Police said the condition of four others was stated to be serious.
Further investigations are on and the bodies have been sent for post-mortem examination.