"He's threatening all of us with a firearm ... He punched my dad in the nose," Shellie Zimmerman said on the call. "I don't know what he's capable of. I'm really scared."
She also said he grabbed an iPad from her hand and smashed it. Her father also declined to press charges, the police chief said.
Police officers could still build a case based on surveillance video from cameras outside the house and also video from the squad cars of officers who responded. Florida law allows police officers to arrest someone for domestic violence without the consent of the victim.
Police spokesman Zach Hudson said the estranged husband and wife were blaming each other for being the aggressor and that police officers were sorting through their accounts.
George Zimmerman's attorney says his client never threatened his estranged wife and her father with a gun even though Shellie Zimmerman reported that in a 911 call.
Mark O'Mara says that the dispute between George and Shellie Zimmerman at her father's house was the result of heightened emotions from their ongoing divorce.
O'Mara says there may be have been some "pushing and touching" but George Zimmerman never punched his father-in-law.
On the 911 call, Shellie Zimmerman says her husband had punched her father in the face and had threatened them with a firearm.
O'Mara says neither side wants to press charges.
Shellie Zimmerman in her divorce filing last week said she and her husband had separated a month after he was acquitted of any crime for fatally shooting the 17-year-old Martin in Sanford, not far from where Monday's investigation happened.
Shellie Zimmerman asked the dispatcher to send an ambulance to check her father out. A fire department ambulance arrived at the house but nobody needed to be transported, Hudson said.
"The call went out as a 911 call that Mr. Zimmerman was threatening them with a firearm," Hudson said. "We're trying to see if that's true or not."
In her divorce petition, Shellie Zimmerman asked that her husband pay for a permanent life insurance policy with her named as the beneficiary, according to a divorce petition made public last week.
In an interview with ABC's Good Morning America that aired last Friday (local time), Zimmerman said her husband left her with "a bunch of pieces of broken glass" after the acquittal. She said he only stayed in their house three or four nights since the trial ended and that they even tried counselling. But she moved out August 13.
"I have a selfish husband and I think George is all about George," she said.
George Zimmerman and his lawyers have made no public statements on the divorce proceedings. An email to Zimmerman's lawyers weren't immediately answered. But lead defence attorney Mark O'Mara was at the home.
Neighbours and other onlookers gathering to watch.
George Zimmerman's brother Robert Zimmerman Jr., tweeted that "we've learned from GZ case not to 'jump to conclusions,' to wait for facts, & to avoid speculation. `News' is a business - not your friend."
- AP