Officers were called to an apartment complex in Altamonte Springs on Wednesday, police said, after someone on the call heard a loud noise and saw 21-year-old Shamaya Lynn fall backwards.
Paramedics arrived at the scene and tried to save Lynn's life, but she was pronounced dead after suffering a gunshot wound to the head.
According to investigators one of Lynn's two young children shot her with an unsecured and loaded gun.
"To anyone and everyone tuning into this story, if you own a firearm, please keep it locked and secured," Officer Roberto Ruiz Jr., an Altamonte Springs police spokesman, said at a news conference. "Incidents like this could be avoided."
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Authorities say the father owns the gun. Detectives are working with the Seminole County State Attorney's Office to determine if any charges are appropriate for the father.
Relatives are now caring for the children.
The CNN Wire contributed to this report.