We saw a strange purple light

Hi, I'd like to share something with you. Last night while we were sending our friend home (my friend and I) the streetlights dimmed the instant we passed under them and then on our way back they lit up again. This was around 10 pm. After that, my friend and I saw some kind of purple light, only for a second. Any advice, any thoughts? It's been happening for 3 days now. Thanks in advance.