I just received the same phone call from a 800-396-1911 and a man named John from The Association for Police and First Responders. He did not mention a "PAC", but the first paragraph of your call matches mine identically. Ironically, I am an on-duty firefighter at our station (where the call was received) as well as our local union president and I questioned their charity as it sounded like pure BS. As soon as I mentioned this, the caller said, "UM Okay, well you have a good day." and hung up.
DO NOT give to ambiguously named "charities" who use police and firefighters as a cover. If it is not a legitimately named charity (usually tied to a local jurisdiction), then please do not fall for this.