I watched this movie when I was a kid in the 70's. Some people were in a cave, maybe scientist, maybe related family, they saw a flash a light come from outside. The vehicle did not start. They started walking. The house they came to, no one around. The clothes were laid out on the bed with a pile of ashes or dust in the middle of it. They walk into town. I think they found this boy in the pickup and a dog was crazy.

This may not pertain to what you're referring to, but, in my little area, about 3 miles from where I live, about 100 yrs ago, everyone in the town disappeared. This has been documented, so it is true. It was a very small village. Everyone disappeared and their houses were left just as they were. Some of their tables were even set with dishes ready for their meal. They just vanished and there has never been an explanation. Perhaps it is possible... I don't know.

It's a TV movie from 1974 called Where Have All The People Gone?

Excellence, I believe this was the title I was looking for. Now I can locate it. Thank you.