Six people, including two labourers, were injured after the roof of a single-storey house collapsed in Rohini’s Prem Nagar Thursday. “When a hammer hit a partition wall, the roof collapsed on the six people. The injured were taken to a hospital and are stable. DCP (Rohini) S D Mishra said the house, which was an old structure, was recently purchased by a family. Prima facie, it appears that the girders were not in good condition,” said Mishra..