It could of been a simple drug interaction from prescription meds.
like i said before, i usually do try to help them unless i know i'm ill equipped to do anything (ie with my 5 y/o nephew or something). but the times i have helped someone:
1) crackhead who grabbed me (i know what crack smells like) and tried to set me on fire with a lighter
2) guy started throwing rocks at me, someone else called the police and he got arrested (the cops told me he was a known angry drunk)
3) guy started shouting obscenities at me at the top of his voice, someone else called the police and i don't know what happened after
4) homeless guy so completely drunk he kept stumbling off the sidewalk into heavy traffic, so i called 911 and sent him to the hospital for the night
5) rape victim who was in terrible shock and had a bad concussion
yes, sometimes they really do honestly need a helping hand, but my point is you need to be careful for the safety of anyone in the vacinity as well your own. if you're not equipped for the possible consequences, get someone else who is then stay the fuck away.