Emergency! Colour run advice

[MabelBee]

I've just managed to colour a whole load of washing purple. Very quickly, do I need to keep the washing wet while I go and buy a colour run remover? Or should I dry it before using something? Should I throw it in some cold water? Or send it round in a cold water wash?

I would keep it wet so the stain doesnt set.

Thanks. That's what I was thinking but just panicking.