The shot woman was taken to a hospital for emergency surgery and is expected to survive, investigators say.
The shooting happened on the 2200 block of Forest Street, authorities said. The gun owner, 41-year-old Brian Siegfried, cocked the gun and left it on a front porch table before walking across the street, according to police.
He told investigators he was "tired of holding the gun and put it down," authorities said.
Four children under the age of five were near the gun before one of them picked it up and shot the victim, police believe. None of the children were hurt.
Siegfried, of Williams Township, is the subject of a protection from abuse order and prohibited from owning a gun, according to authorities.
He is charged with aggravated assault, five counts of reckless endangerment, and persons not to possess a firearm, they added. His bail was set at $25,000 and his preliminary hearing is scheduled for July 15, according to his latest court docket.
Click here to follow Daily Voice Pennside-Mount Penn and receive free news updates.