Police said they tried to subdue Earl Rhodes, 48, with bean bags, then a stun gun, but he kept coming at them and eventually tried to grab their weapons, forcing officers to shoot and kill him.
According to a neighbor identified as "J.W.", Rhodes was sitting on the porch when police shot him with the bean bags.
"It irritated him to come, not like a charge, at them, and they started shooting with real bullets," he said.
Mabel Rhodes said her son is bipolar and had been off his medicine.
She said he became loud and aggravated. Rhodes said she dialed 911 hoping police would come and take him to a hospital.
"They shot him six times in cold blood," said the man's brother, Charlie Lewis.
Police maintain they had no choice.
"They knew he suffered from a mental illness," said Sgt. Mitzi Grasso of the Los Angeles Police Department. "He became very aggressive toward the officers. He attacked the officers and was trying to get their guns. Because of his aggressive actions, the officers shot him.
"The officers had minor injuries, scrapes and abrasions, so he did come in contact with the officers. He did start fighting with them. They tried all the less than lethal means."
The shooting remains under investigation.