There is not enough information. We don't know who fired first. We don't know what the resident said to the cops. I do not have specific knowledge of Florida laws but would you think the cops culpable if the resident fired first? Does a Florida homeowner have a legal right to shoot anyone in his yard who fails to leave when ordered to?
Florida follows the "reasonable man" standard, so the answer is "yes" in the correct circumstances.
If cops would wear uniforms and drive marked vehicles when doing cop work, there would be no need for more information, and grandpa would probably still be alive.