The incident occurred at Vasant Nagar where nearly 10 labourers were engaged in construction work on the arch which suddenly collapsed resulting in spot death of Dharma Rao and Nagabhushan, Cyberabad West Zone Police Commissioner Navin Chand said.
While two labourers belonged to Srikakulam in Andhra Pradesh, one of victim hailed from Odisha, he said.
The other four labourers injured in the mishap were admitted to a nearby hospital. They are in the process of registering a case and have picked up some persons for interrogation, the officer said.
Meanwhile, GHMC Commissioner B Janardhan Reddy has ordered an enquiry into the incident and directed the chief city planner to submit a report immediately.
The deceased were in the age group of 45 to 55, GHMC officials said, adding the arch was being constructed for a gated residential community, without permission.