Who do I report this to?

Found out a very abusive couple are driving their kids around in a truck without brakes. They are using the emergency brake for regular stopping. The inspection was done nearly 6 months ago, when the brakes worked. We've tried to get social services involved several times for the condition these kids live in and treatment but to my knowledge they haven't even followed up. But seriously, who do I report the dangerous truck to?

We no longer live in the same town so I can't report them when I see them out and about in the truck.

Anonymously since there's a good chance the female will see this.