Hyderabad- A police constable was killed and 13 other people including an Assistant Sub Inspector injured in an exchange of fire between two groups. Police said two groups opened fire after quarrel during a procession, taken out in connection with birth anniversary of Hazrat Ali (R.A) within the limits of City police station. As a result, gunman of DSP City was killed and ASI Adam Ali Khushak and 12 others sustained injuries. The injured have been shifted to Liaquat University Hospital where condition of three is said to be critical. Rangers have been deployed to avert any untoward incident as tension gripped the area following the incident.