Graphic video released Thursday shows a crazed gang member using two large knives to slash a female office worker during a stabbing rampage in Southern California in which he allegedly killed four people.

The 54-year-old woman can be seen sitting in a small insurance office when a man in a blue hoodie comes up to her and pulls out the blades, in the horrifying footage released by Garden Grove police.

The woman can be seen throwing up her arms to shield herself as the maniac repeatedly stabs her — before eventually fleeing to crouch behind a nearby desk.

Meanwhile, the psycho appears to grab something from the office before making a run for it.

The woman, who wasn’t publicly identified, was stabbed several times, but was expected to survive.

She “was very brave,” said Garden Grove police Lt. Carl Whitney. “She fought as best she could.”

Cops say her attacker, Zachary Castaneda, killed four people Wednesday during a two-hour stabbing and robbery spree.

The violence appeared to be random, while the motive seemed to be “robbery, hate, homicide,” said Whitney.

When cops arrested Castaneda, 33, Wednesday outside a convenience store in Santa Ana, he was covered in blood and had allegedly just killed a security guard and stolen his gun.

He “could have injured or killed many other people,” Garden Grove Police Chief Tom DaRe said. “He remained violent with us through the night. He never told us why he did this.”

Court records show Castaneda was free on bail at the time of his rampage for a charge last month of carrying a concealed dagger.

That charge came when he was on bail for a June arrest for street gang vandalism.

His mile-long rap sheet includes prison stints for car theft, and for possession of meth for sale while armed with an assault rifle.

With Post wires