The Winnebago County Sheriff's Office said Jimmy Hurn was with his two-year-old daughter Thursday when she found the bullet in his car.
Hurn told authorities his daughter then lodged the bullet in the charger port, causing it to discharge.
The bullet struck the toddler in the eye, WIFR reports.
The girl was rushed to an area hospital before being transferred to another, where she reportedly underwent surgery Thursday night.
A message left with UW-Madison Hospital regarding the girl's condition was not immediately returned Saturday.
Police said Friday the incident remains under investigation.
- Source: Inside Edition