No, do NOT call CPS. They are corrupt to the bone. Instead, I would suggest either offering to keep the children and talking with the parents. Who knows, they might have a babysitter that you're just not aware of. Make absolutely certain that you know what you're talking about before making any kind of allegations against them or anyone else. There are far better ways of taking care of this than calling CPS. They'll remove the children and place them into foster care. Do you really want this on your conscious, especially without knowing all the facts? Think long and hard on this. If you are really so thoughtful and caring as you seem to be, then why not babysit for them? The economy these days are bad and any offer of help might just be appreciated.
If, in fact, they are abusing or neglecting these children, then call the police. Child abuse/neglect is a CRIME and should be handled by police or other law enforcement officers.