Maybe one kid with a good immagination but a number ... they saw something.
I go with the con trails.
When I was a kid in the fifties my father was in England and came home with a story of seeing contrails lit up by the sun when it was almost dark on the ground and how striking it was for him.
He was over there doing the Viscount course prior to bringing one of them back to Oz. He'd flown prior and during the war, so, had seen plenty of interesting things yet this one stoked him.
Sunset was a smidgen past 6 PM amd the clouds in shadow would be contrasty with lit up contrails.