Anti-Terrorism Squad
In India , Anti-Terrorism Squads (ATS) are special counterterrorism units present in several  state police agencies of India including Maharashtra Police, Gujarat Police, Kerala Police, Uttar Pradesh Police, Rajasthan Police, Bihar Police, Jharkhand Police ,Tamil Nadu Police, Madhya Pradesh Police and Chhattisgarh Police. These units are frequently involved in the investigative, intelligence and emergency response aspects related to terrorism and cooperate with other branches of their police departments, police forces from other states, and national agencies such as the Intelligence Bureau and the National Investigation Agency. The first Anti-Terrorism Squad of India was founded in Maharashtra in 1990 by the then Additional Commissioner of Police, Mumbai Aftab Ahmed Khan (popularly known as A.A. Khan). He was inspired by the Los Angeles Police Department's Special Weapons & Tactics (SWAT) team's methods to combat modern-day terrorism. Since then Anti-Terrorism Squads have been integrated into the police departments of numerous states, with the original ATS of Maharashtra Police being terminated and then reconstituted. History
The ATS was formed in December 1990 and helped reduce the crime rate in Mumbai by 70%. However, there were many human rights violations by the squad, from extreme means of torture to public shootings. Following the 1991 Lokhandwala Complex shootout on 16 November 1991 and many more encounters, the organization was terminated in January 1993. The leader of this program, A.A. Khan, was transferred from his position as the chief of Mumbai's ATD to the IGP (Anti Naxalite division) to Nagpur on 29 January 1993 following the termination of the program. One month later on 12 March 1993 the Bombay blasts occurred, and the crime rate has increased since then. The Anti Terrorism Squad of Maharashtra Police was later reinstated in the states police department by the Government of Maharashtra, vide G.R. No. SAS-10/03/15/SB-IV,
dated 8 July 2004. By state

Maharashtra
Maharashtra Police was the first police department in the country to set up an ATS unit. Although the unit was disbanded in 1993, it was later reinducted in the state's police force in 2004 as a special unit of Maharashtra Police.In 2008  ATS chief Hemant Karkare was killed in the line of duty fighting against terrorists in the 26/11 Mumbai attacks.The Anti Terrorism Squad of Maharashtra Police is frequently involved in combating the intelligence and investigation challenges related to terrorism but not armed anti terror operations , which are usually undertaken by other police units. Uttar Pradesh
The U.P. created its own Anti Terror Squad in 2007.Although the anti terrorism squad of U.P. generally deals with the intelligence aspects of terrorism  it has been stepping  up its tactical counterrorism capabilities sinces 2017 with creation of tactical units called Special Police Operations Team (SPOT). West Bengal
Kolkata Police had two anti-terrorist squads much before the police forces in Delhi and Mumbai came up with the idea. It is another matter that these two units turned out to be woefully inadequate in tackling modern-day terrorism. By the time, the administration realized this and merged them to set up the Special Task Force (STF).In 2008 ATS/STF, Kolkata Police captured most wanted Indian Mujahideen Co-founder Yasin Bhatkal for a case involving large amounts of fake currency. Role

