Actually, that info sounds wrong, nix. If there was a pitbull terrier on the loose, the police would've dealt with it, I'm sure. It's illegal to breed these dogs, except under very strict conditions, and any let loose in public must be muzzled, chipped and insured. You say that one is "probably" crossed with a pitbull? Pits are cross-bred anyway, to get the breed that we know, and there are similar-looking animals, such as Staffies and crosses of. I agree with paraffin, that the RSPCA might be the best ones to contact, or the Council dog warden when you're able to contact that department.