It looks like ICE saw that the man was armed, and shot him. Being armed is legal, and just being armed doesn’t make someone a threat. ICE started the physical altercation with him and he doesn’t seem to be reaching for his gun or anything like that, although the video isn’t clear.
Like Renee Good, the Trump administration blatantly lied about the situation, giving us no confidence that the situation will be properly investigated. Blatantly lying about the state killing a citizen is a hallmark sign of a tyranny.