A SIT-IN by rooftop dwellers fighting a government clearance degenerated into violence yesterday as protesters scuffled with police. Violence erupted as Buildings Department officials left the Nathan Road scene after agreeing on a reprieve, letting the dwellers stay until May 6. Supporters lay on the road to block the departure of Assistant Director of Buildings Lok Che-leung, who had led staff to hand removal orders to the 31 rooftop families. About 30 policemen and police tactical unit officers had to form a human wall so Mr Lok could leave in his car. Social worker Chow Shue-tak, who was wrestled to the ground during the scuffles, later claimed he had been hit by Mr Lok's car. Mr Chow was treated at Kwong Wah Hospital for a twisted ankle. The rooftop families should have moved out by yesterday. About half of them stayed put in protest against having to move to temporary housing areas. They want public rental units in the same district. The clearance was prompted after complaints by residents about water seepage and cracks on walls. Mr Lok said: 'We decided to delay the clearance because we want to allow the affected residents more time to pack their belongings and to discuss rehousing with the Housing Department.' One residents' representative, Yu Yuk-wa, said they would resist future deadlines.