A while back, I was on public transit and I saw an older woman coming unglued during conversation with the bus driver about a bag she lost on a bus. She was staying in a shelter that had a curfew and had lost a bag with her ID, money, medications in it, and was about to be late for curfew. I saw that people were veering away, looking away, pretending to ignore the commotion she was causing and I responded by getting angry, myself, so I got up from my seat, took a deep breath to compose myself - then started mediating the conversation as best I could.
The lady was receiving very little empathetic response from the driver because she was crying and was really overwhelmed (not able to speak very clearly through her tears and anxiety) prior to my interference - both were just not able to understand one another due to the emotional impact this situation had on the lady.
I got her to calm down, asked the driver for a clear set of instructions for this woman to follow in order to recover her lost/mis-placed bag - which had been found and stowed safely by another bus driver. I wrote down what I thought I wouldn't remember for more than 5 minutes as I realized I couldn't just leave this lady, for even a moment, in her vulnerable state.
The bus had to depart, so I got off the bus with the overwhelmed lady and promised to stay with her until the other bus with her bag had run its circuit and returned to a certain stop.
The issue of shelter curfew came up so I phoned the place directly, explained who I was and what was happening and promised to stay with the lady until everything matched up. The shelter treated the situation as a special circumstance and said they would allow the resident to enter after curfew because of the unusual circumstance.
The lady and I waited, got her bag back, then I went with her on another bus trip to the shelter with her to make sure the shelter would allow her to enter. Shelter staff did open the door right away for her and then I went home and was able to sleep well that night because I hadn't ignored a situation where someone very apparently and visibly needed help.