NELLORE:Three workers died of suffocation and two others were critically injured in a gas leak at Indus Coffee Factory, located in Special Economic Zone (SEZ) of Mambattu village in Tada mandal on Tuesday. The deceased were identified as C Ravindra Kumar (26), E Ravi (25) and C Eeswaraiah. According to the police, when the workers were cleaning a deep boiler, a valve accidentally got delinked from the bolier, which resulted in gas leak. A case has been registered by the Tada police.