There's no word if anyone was wounded. Sheriff's officials said a 16-year-old boy was taken into custody.
The sheriff's office said students have been removed from the school and that an investigation is ongoing.
Assisting Italy PD and DPS is the Ellis County Sheriff Office, Hill County Sheriff Office, and the Texas Rangers.
Authorities are reporting a shooting near a school in North Texas Monday morning.
Ellis County Sheriff's Office now has a 16-year-old male suspect, a fellow IHS student, in custody.
Ellis County police did say a media area was being set up near the scene.More news: Hotel bans 'social media influencers' after woman asks for free stay
There is only one high school in the town.
The victim was airlifted to a nearby hospital and her condition is not known. The incident happened at approximately 7:53 a.m. local time.
Schools chief Lee Joffre said the shooter left the building immediately after opening fire.
Joffre said the district was working to make sure grief counseling was available for students.
Italy is 15 miles south of Waxahachie, in Ellis County, and 44 miles south of Dallas. Murray declined to release additional details.