I'm gonna post what I posted five minutes ago when you made this thread in A&S.

Here's what you do:

1. Remove yourself from harm.

2. Call the police.

Step two is more effective if you took the plates between the event and step one. In either case, the single worst thing you can do expend energy immersing yourself further into the situation, rather than extricating yourself from it.

Other general strategies I use to avoid such situations are staying away from large or heavily trafficked roads. If you live in a bike-lane/sidewalk/MUP-friendly town, I'd suggest employing those options in place of large streets whenever possible.