The Cherokee County Sheriff's Office said in a news release that the boy's great-great-grandmother called 911 on Wednesday afternoon.
The Tyler Morning Telegraph reports that details, including how the toddler found the gun, are still under investigation.
Officials say the boy, who would have turned 3 in July, shot himself with a 9mm pistol.
He was taken by helicopter to a Tyler hospital.
Viewers with disabilities can get assistance accessing this station's FCC Public Inspection File by contacting the station with the information listed below. Questions or concerns relating to the accessibility of the FCC's online public file system should be directed to the FCC at 888-225-5322, 888-835-5322 (TTY), or email@example.com.