A knife-wielding madman stabbed multiple people, including a cop, at an anti-Islamist political rally in Germany on Friday in a frenzied attack that was caught on a YouTube livestream.

The bloody mayhem erupted in the middle of a square in the city of Mannheim just after 11:30 a.m. local time as members of the right-wing campaign group, Citizens’ Movement Pax Europa (BPE), were filming a demonstration, news outlet Bild reported.

The stomach-churning livestream showed the moment chaos broke out as the bearded knifeman abruptly tackled one of the victims — believed to be the group’s leader, Michael Stürzenberger — to the ground and violently started plunging a large blade into him.

Screaming onlookers rushed in to try and drag the attacker away but he broke free and continued swinging the knife at the original victim.

As the attack escalated, the knifeman started wildly stabbing those nearby and, at one point, sunk the blade into a police officer’s back.

The perp was eventually shot by cops, the graphic video shows.

It wasn’t immediately clear how many people were hurt, or the extent of their injuries.

The condition of the attacker also wasn’t known.

The livestream, which was broadcast on BPE’s YouTube page, showed paramedics frantically rendering first aid to victims in the wake of the attack.

Mannheim cops confirmed there was a “major police operation” in the square but wouldn’t provide further details.

“A firearm was used against the attacker,” police said in a brief statement.

A rescue helicopter was also brought in and trams in the area had been suspended.