Dear Doing,
It is too conflicting to guess what went on here. The point (Not my point. I think GH mentioned it.) is, that the kids were not props. But going by only the video, they may as well have been mannequins.
If they would have paid more attention (Maybe they did.) they could have had more restraint (Maybe that was not an option). The police where acting like he is about to blow up town hall. He is walking toward a car that has his kids in it.