Thanks for asking @lomine . Some died unexpectedly. I suspect from eating a mushroom or something? And my uncle took the rest to his farm because mom didn't want to have to pay someone to watch just 2 chickens when we were out of town. I honestly don't know what could have killed them. They got a wormer regularly, their food was clean, the coop and run were kept clean, water too. It was unexpected and very disturbing.
Perhaps mention this incident to your mom along with a solution to ensure something similar won’t happen again.