At least 119 policemen have been killed in separate incidents of violence and target killings by terrorists and various mafias active in Pakistan\'s southern port city of Karachi since the beginning of this year, police officials said Tuesday.Ghulam Qadir Thebo, the Additional Inspector General Police ( AIG) Karachi, said in a media briefing that policemen are being targeted frequently in the city due to which policing has become the toughest job in the present scenario.He said that a large quantity of illegal weapons are present in the city due to which police is facing a big challenge to maintain law and order situation in the city that is house to over 20 million people.The AIG said that despite all odds, Karachi police have arrested 81 extortionists and recovered 4,077 different types of weapons from them.He said that 22 kidnappers have been killed during multiple police encounters in the city over the last eight months.The deteriorating law and order situation persists in Karachi this year where over 1,726 have been killed in separate incidents of violence, according to Human Rights Commission of Pakistan.Prime Minister Nawaz Sharif arrived on a two-day visit to Karachi on Tuesday where he would meet with different Karachi- based political leaders to discuss the law and order situation in the city.