You do a good job of capturing the proper tone for this sort of report. If your report is supposed to contain proper spelling, punctuation and grammar, you'll need to make a few corrections.
It was about 5 a.m. and i was driving along the main st. approching toward main st. stop,
- "I" should always be capitalized; proper nouns like "Main St." should, also.
when i heard people shouting and screaming "stop the bus, stop the bus", when i looked through the mirror what i found was pretty disturbing. -- A run-on sentence. Better is: "stop the bus, stop the bus!" When I looked in the mirror ..." [one doesn't generally look through
A white male about 6' tall was held down by a group of regular commuters. So i pulled my bus on the side of the road stopped it. Fragment; put a comma after commuters and add "and" after "road."
As i approached to that group and incident as described by almost all of them was pretty shocking. That young thug looked like fella snatched purse from an old women in her 80's and tried to ran away as the bus going to stop. But Luckily intervened by closely standing a young smartian and then held by the group. -- None of these three sentences makes sense. I'm not sure if you're trying to give an abbreviated sort of grammar to simulate a report, or what, but even so, it does not make grammatical sense. Also, I'm guessing you meant "samaritan."
So i called dispatcher, [add comma] described incident and asked him to inform police so that we could turn
him in. But as advised by dispatcher i drove my bus to nearby police station, which was only a block away, because the purse snacher wasn't so agrresive and nobody from bus object either. -- This sounds very unlikely to me; I don't think the public would be put at risk like that. Also "aggressive" is spelled wrong.
After turning him in and filling report i proceed to my route. But this whole incident cost 30 min. delay to operation. -- Usually, if you start a sentence with "But" it's going to end up being a sentence fragment, as this is. Leave off the "But" and it'll be all right. To keep your tenses consistent, say "I proceeded ..."
You have a good start here; keep up the good work!