First, contact as many people as you can, especially local ICE watch orgs. A lot have hotlines which you may be able to find with a web search. Next start recording. Delay as long as possible. Ask for a warrant, stay calm and maybe try to negotiate as a stall tactic. This will hopefully give community members time to arrive and record or hopefully apply pressure if they are brave and numerous enough. It is possible to intimidate and drive them back with enough numbers.

All else fails at this point I would not fight back and allow yourself to be arrested. Most citizens being arrested right now are being released. The courts are slow but still upholding the law for now. If you are not a citizen then your options might not be as good. Fighting back is likely to get you injured or killed but if you have an escape route it could be worthwhile, especially if you can escape in areas where motor vehicles can’t go. Their level of fitness is generally low so they can’t give chase for long, and as long as you’re not high profile you might be safe once you get away, though you’ll likely need to lie low somewhere.

If you’re asking what to do about the current political situation in a broader sense then I have different answers.