A Florida mother whose son, 2, apparently shot and killed his father is now facing manslaughter charges, after investigators determined that the gun hadn't been stored properly in their home.

"These tragedies are 100 percent preventable," Orange County Sheriff John Mina said. Gun owners who don't safely secure their weapons, he said, "are just one split second away from one of these tragedies happening in their homes."

The shooting happened on May 26, when a 911 call of a shooting brought sheriff's deputies to a home in east Orlando shared by Reggie Mabry, his wife, Marie Ayala, and three children, from ages five months to five years.

The deputies found Ayala performing CPR on her husband, who had been shot, Mina said. But Mabry, 26, was pronounced dead after first responders took him to a local hospital.

"It was initially thought based on the evidence that this could be a suicide," Mina said.

But at the hospital, homicide detectives learned Mabry had been shot in the back. And, the sheriff said, "the five-year-old told the authorities it was his two-year-old brother who shot their father."

The gun was left in a room the couple shared with their children and was "easily accessible even to a two-year-old," Mina said.

Investigators also learned that both Ayala and Mabry were convicted felons, and were thus barred from possessing a firearm. The sheriff did not provide an explanation for how the pair of felons were able to obtain the gun.

Under Florida law, loaded firearms must be stored in a locked box or a similar spot, or disabled with a trigger lock if they're in an area where a child under 16 can reach them.

"Now these young children have effectively lost both of their parents," Mina said. "Their father is dead. Their mother is in jail, and a young child has to live their life knowing that he shot his father."

Mina also noted that when Mabry died, the couple was on probation for child neglect and narcotics offenses.

Ayala, 28, now faces several charges, including manslaughter by culpable negligence, possession of a firearm and ammunition by a convicted felon, and violating her probation.