As pointed out, this was more out of neccesity than anything else- there is a reason the first SWAT team in the world was the LAPD's. Such units in the US are used for everything from drug raids to armed robbery response and counter terrorism is simply on top of that. In India these units were only raised after 26/11 and their primary role is Counter Terrorism, they are not used (or at least almost never) for regular police duties as they are in the US.
yeah,because india dont got civilian firearms market like usa,
so thats why on indian streets illegal or even legal firearms are absent,
usa has gun culture which promoted their gun market and like any other usa market its got hugh demand and supply,
and also there always been black market at any business and usa gun market is no exception,
so a lots of illegal firearms at american streets and its being used for crime,
and thats why they are the first ones who required such tactical police teams much before wtc terror,
and these teams are used on daily basis even if there is no terrorism.