Trust me, it takes less than a nanosecond for a kidlet with a scissors to do that kind of damage.
Agreed. It’s not like they are toddlers that you shouldn’t turn your back for a second. So I wouldn’t say they were unsupervised. They are 7 or 8 now, you can leave them to play by themselves and be in the next room.
Well, kids will be kids, and can still do unexpected things....
My mom, but also other parents I have heard, often remarked that you need to check when your (grand)children go quiet. It could have gone wrong, but it can also be that they have been up to something.