UPDATE 12:35 PM: And here's CNN, which says there was an "apparent domestic altercation," and that a gun was found in the home, but was "not a part of the altercation."
UPDATE 1:40 PM: ThinkProgress posted the 911 call to SoundCloud. Shellie Zimmerman says George Zimmerman punched her father, broke an iPad, and threatened them both. Here's the call:
ThinkProgress also reports that "Police Chief Steve Bracknell said, '[Shellie Zimmerman and her father] both have declined to press charges against George Zimmerman. We have no victim, no crime.'" Zimmerman is free to go, but police have kept his gun.