We have been raising chicks for a few month now. I have an 4by 8 brooder on the ground in the back yard put chicks out at 3 weeks since weather is upper 80's to mid 90's in the brooder I had 20 chicks from 4 to 6 weeks old today my wife opened top to check on them. She said before her eyes some started falling over dead 8 in all not sure what's going on. It happens in a span of a couple min and that was it.