If you watch the video he manages to stop at a police cruiser after the MRAPs pass him by. The Cruiser was probably aware of him calling in, but they sent the MRAPs to respond to the second shooting. The police were only given an explanation for the first shooting (before Kyle's call), so dispatched units for the second one. Their rules of engagement are probably to only interfere if people start obviously killing each other.
You can see him doing just that in the screenshot.
That isn't really an "interaction". He held his hands up for them to come get him, but they didn't try to.
If you watch the video he manages to stop at a police cruiser after the MRAPs pass him by. The Cruiser was probably aware of him calling in, but they sent the MRAPs to respond to the second shooting. The police were only given an explanation for the first shooting (before Kyle's call), so dispatched units for the second one. Their rules of engagement are probably to only interfere if people start obviously killing each other.