ARLINGTON, Texas (CBSDFW.COM) – Four people were injured during the shooting at Timberview High School Wednesday, Oct 6, according to the Arlington Police Department.

All are expected to recover.

Investigators say one adult, believed to have been hurt in a fall when shots rang out, was treated and released at the scene for minor injuries.

Three victims were taken to Medical City Arlington.

A teenage girl was treated for abrasions and released.

Arlington’s Asst. Police Chief Kevin Kolby says she was grazed by a bullet or injured in some other way.

The other two victims were hit by gunfire and remain in the hospital, as of Wednesday evening.

According to police, the 15-year-old student injured is in critical condition in the ICU.

He had to undergo surgery for his gunshot wounds.

A 25-year-old teacher, identified by his family as Calvin Pettitt, was also shot but is in good condition.

Calvin Pettitt (credit: Pettitt family)

His sister says the shooting didn’t happen in his classroom, but Pettitt came to help break up the fight and got hit.

She says the bullet went in his back and barely missed his aorta.

Pettitt apparently has some broken ribs and a collapsed lung and is expected to be in the hospital for a few days.

He teaches English at Timberview High.

“Mr. Pettitt – very nice teacher,” said student Ashlyn Henson, who was in one of his classes last year. “He’s very encouraging, and I do miss his teaching because he was the teacher who encouraged me to start writing because he saw something in me.”

Henson says she also knows the 15-year-old who got shot, and called him a special person.

“I just want them to come home safe, like everybody else,” she said. “We all got to come home, and I want them to do the same.”

Caroline Vandergriff