London - Police in London are asking for the public's help after an apparent random attack on a sidewalk there.

We'll warn you- some of you may find this surveillance video graphic.

As you can see a woman is walking alone on the sidewalk, when a man approaches her from behind.

The man punches her in the side of her head, apparently knocking her out.

He ran off after the brutal attack.

Police have released a description in hopes that someone who knows him will come forward.

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