Hi - I am hoping someone can help us. Either they have seen it before or could advise what we could do. We have hatched a few lots of chickens - so far our success rate has been pretty good. All chickens doing well, growing and going off to new homes as they get bigger. A few specials staying in our family. Then suddenly this morning our 2 week old chicks started to die. They were gasping then convulsing and dying within minutes. I rushed home to my distraught daughter to assist. We removed the ok chicks from brooder box and cleaned it immediately (was only cleaned 2 days earlier) I cleaned their water and food and everything was perfectly fine at 6am - then dying at 8am????? We then checked on our 2 x 5 week old chicks in another room and one of them was panting. We took them outside for fresh air and one of them died within ten minutes. Everything has been the same for all our babies and they were all going really well. No pasty butt, no lethargic chicks, Healthy bright looking chicks. The 5 week old one was following us around yesterday like it did every day and was pecking my hand and sitting on the edge of the box while I gave him fresh food and water this morning. Has anyone any idea of what happened??? I thought it must have been gas leak or something but apparently gas is fine. Any help would be appreciated - we are devastated!!