It made chlorine dioxide gas which is extremely toxic. It will sear the lining off of your nose, throat and lungs causing chemical pneumonia that can result in death.
It’s not very different than the poison “mustard gas” used in WWI that killed thousands.
Happened to my dad. Co-worker decanted some muriatic and didnt label it, pops poured it in assuming it was what was marked on bottle.
Had to evacuate building,was on local news. Dad ended up in hospital and Festus almost got fired.