One worker was killed and three others were injured in an explosion at a steel factory in IDA Bollarum on the outskirts of Hyderabad on Wednesday. The mishap is suspected to have been caused by the explosion of the boiler. The injured were shifted to a hospital at Kukatpally in Hyderabad, where their condition is stated to be critical. The deceased was identified as Hemanth (28). The body was shifted to a government hospital at Patancheru for autopsy. Police rushed to the area and took up investigation. The cause of the blast and other details are awaited.IDA Bollarum is an industrial cluster located in Sangareddy district near Hyderabad and has seen some industrial accidents in the past.