Seed production in the middle of flowering without any male plants

100 km ;))))))))))))))))))))))))))))))) 10 km is counted safe, there were studies, some info you can find here : https://www.canr.msu.edu/news/weighing-the-risk-of-cannabis-cross-pollination my outdoors second wave plants were polinated too, just some male or hermie was not far .... its still weed, just no grinding with equipment, only by hands, taste like shit if seeds crushed.

You can only get seeds if there is a male plant or male flower somewhere. Females can not produce seeds through "immaculate conception", there must be a source of male pollen. As others have said, pollen can travel vast distances on the wind. A single male flower hidden on one of your plants could also be responsible, they can appear and disappear without you noticing, quite easily. Judging by your pictures and the size of the developing seeds, it seems as though pollination occured about 3 weeks ago. Without knowing exactly how they came to be, it would be very foolish to grow any viable seeds you might find.

Pollen can travel hundreds of kilometers, sometimes thousands in the wind. You don't need to be near a male plant to get seeds, but the closer one is the more seeds you'll have. This is why growing a male outdoors is a very selfish thing to do, you can ruin many grows around you.

Pollen can be transported through air or insects as well, so you dont need to have male flowers/plants yourself for this to happen. Maybe your area was "contaminated", could be coming from a neighbor too for exampl. But often it is a single / a few male flowers somewhere in your plants which is hard to notice