San Leandro police say the 12-year-old boy was visiting his family from out of state when Hammond stabbed him inside the bank.
"I can only imagine what this boy is going through," said Lt. Robert McManus. "The shock, the scare."
Police say Hammond stabbed the boy 3 times with scissors. The most severe wound is in his upper back near his neck.
"The wound itself was fairly deep and it will require surgery," McManus said.
Police say Hammond then demanded money from customers. She robbed one customer who was at the bank to make a cash deposit of a few hundred dollars
"At some point she got very enraged and agitated and she walked over to the boy who was sitting in a chair, peaceful, waiting for his family member to complete their meeting that they had there at the bank when she stabbed him from behind, it was completely unprovoked," said McManus.
The bank had two unarmed uniformed security guards inside. It's unclear when, if at all, they intervened.
The boy is in stable condition at Children's Hospital in Oakland. Police say Hammond who is now in custody may have also hurt herself.
She was initially facing charges of assault with a deadly weapon but those charges were upgraded to attempted murder due to the severity and location of the boy's wounds. Police also because the assault was unprovoked and Hammond attacked the boy from behind.
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Iyona Hammond of Oakland faces robbery & attempted murder charges, police say stabbed 12 yr old at San Leandro bank pic.twitter.com/Xm5n5BrgyE— Melanie Woodrow (@MelanieWoodrow) June 6, 2016
Boy needs surgery. Unclear why unarmed security guards didn't intercept woman after she began demanding money but before she stabbed boy— Melanie Woodrow (@MelanieWoodrow) June 6, 2016
Police working with Wells Fargo to get security video. Boy was stabbed in back from behind near neck 3 times, he thought he was punched— Melanie Woodrow (@MelanieWoodrow) June 6, 2016
Two unarmed uniformed security guards were inside. Unclear if woman was armed with scissors or knife. LE fingerprinting woman for ID now— Melanie Woodrow (@MelanieWoodrow) June 6, 2016
Boy in stable condition, 32 year old female suspect is in custody, robbed a customer of few hundred dollars and stabbed boy from behind— Melanie Woodrow (@MelanieWoodrow) June 6, 2016