A man in Los Angeles died Friday night after cutting off his own genitalia ... TMZ has confirmed.

The Los Angeles Police Department received a call about a man harming himself in Downtown Los Angeles around 3:40 AM.

After arriving on the scene, they set up a white tent to keep onlookers from seeing the man's body ... though a videographer at the scene captured pools of blood staining the sidewalk.

Law enforcement sources tell TMZ ... the man cut off his penis, sliced his throat and stabbed himself with a sharp instrument. We're told he also tried to cut off his arm.

It's unclear at this time what he used to harm himself. Officers also do not know the man's motivation ... or if he was on drugs at the time.

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