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.