A Brazilian schoolgirl was held Monday night for knifing 30 men to death.

The 17-year-old stunned cops by owning up to a serial killing spree that started when she was 15.

She told detectives she wanted to confess before she turned 18 and could be tried as an adult.

The girl – who can't be named because she is still a minor – said she began targeting men in her home city of Sao Paulo, Brazil "for money, revenge and to bring justice."

She even smiled as she reeled off her list of victims - which is feared to make her the world's most prolific teenage serial killer. She calmly bragged to police: "I don't have enough courage to hold a gun — but I can hold a knife.

"I am confessing because I promised I would do so before becoming 18 — to avoid upsetting my family."

The teen told how she always used the same knife — butchering one man for throwing a glass of brandy in her face in a bar fight.

But police are still unclear about what drove her to keep on killing.

Sources said one theory is she was hired by gangland bosses as an assassin because she was so innocent-looking. The teenager's sensational confession came after she was arrested over a Sao Paulo street fight.

It shocked a country still reeling from the arrest of a TV crime show host for allegedly arranging killings to boost ratings.

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