Police say they went to the Gage Park home on Monday because someone was violating an order of protection. They say Hernandez had a knife and was threatening to hurt himself.
Officers apparently tried use a stun gun on him, but it didn't work. He then reportedly grabbed a butcher knife. Police say they then shot him because they were concerned about others in the house.
"The Chicago Police Department serves and protects and those innocent people were the ones they were protecting," said Pat Camden, spokesperson, Fraternal Order of Police.
"Do they needed to kill him? It was one knife. Don't we have trained police or do we just got killers with badges?" said Hernandaz's father.
ABC7 cameras later caught the police union spokesperson talking to the suspect's family. He was heard saying they were being unfair to police.