At least six persons, including a political party worker, were killed in various incidents of violence in southern Pakistani city Karachi on Tuesday. According to police, at least three persons were killed in a gun-firing incident in Orangi town area of Karachi. Unknown assailants who came on motorbikes opened fire near Islam Chowk in Orangi town area killing three persons including an office bearer of a political party. The markets and shops in the locality were closed immediately after the attack as fear gripped the area. Another person was gunned down near Mohajir chowk in the same area shortly after the first incident, said police. Another incident of violence occurred where militants attacked police while conducting an operation in Karachi\'s Musharraf colony area. The police retaliated the fire killing two suspected criminals and recovered two TT pistols and a stolen motorcycle from the possession of the militants. Meanwhile, the spokesperson for Rangers Sindh told that over 19 suspects were arrested during operations conducted in Chanesar Goth, Shah Faisal, Green Town, Rasheedabad, Taiser town, North Karachi, Quaid-i-Azam colony and North Nazimabad areas of Karachi. Police has claimed to arrest eight criminals from different areas of the city. Police also claimed to have detained four militants belonging to the banned Lashkar-i-Jhangvi outfit and five target killers during operations conducted in Karachi. Earlier, the Federal Cabinet approved an operation led by the paramilitary Rangers force Karachi against the militants creating lawlessness in Karachi. The largest Pakistani city Karachi has been a target of violence from last few years and according to Human Rights Commission of Pakistan resulted in killings of 1726 people in first six months of 2013.