The two killed labourers included a woman from West Bengal.
Some labourers are feared trapped under the debris, which the authorities were removing and trying to rescue those buried alive, officials said.
The accident occurred in Film Nagar, where the three-storey building was being built as part of the expansion of Film Nagar Cultural Centre and cement-concrete slabs for two floors were laid.
Eight injured persons rescued by locals soon after the collapse around 12.30 p.m were shifted to the nearby Apollo Hospital.
Police, fire services and Greater Hyderabad Municipal Corporation (GHMC) launched the rescue operation. The National Disaster Response Force (NDRF) also joined the operation.
A GHMC official said no permission was given for constructing the building as the land’s ownership was disputed and the case was pending in the court.
Greater Hyderabad Mayor B.Rammohan visited the scene.