1) Apparently the parents were forced by CPS to sign a "safety plan" agreeing not to let the children play unsupervised until CPS could marshal their full administrative resources to review the case. When the father at first refused, the CPS official said they'd take the kids if he didn't sign the contract. This is a strange sort of "agreement." Obviously, it's not voluntary in any sense of the word, and coercive in every sense of that word. Kafkaesque.
2) The Washington Post leaves out the details of what happened when the police came:
The police asked for the father’s ID and when he refused, called six patrol cars as backup. Alexander went upstairs and the police called out that if he came down with anything else in his hand “shots would be fired,” according to Alexander. (They said this in front of the children, Alexander says).At least they didn't specifically threaten to kill the kids.
3) In America, black people get shot for walking in the street. I guess white people might get shot for letting their kids walk alone where there might be black people.