Police identified the suspected gunman who stormed YES Prep Southwest Secondary school in Houston, Texas, on Friday and wounded the principal as 25-year old Dexter Harold Kelsey.

Kelsey has been charged with aggravated assault against a public servant and deadly conduct in the 263rd State District Court, Houston Police announced Saturday.

Houston police said a call about reports of an active shooting came in at 11:45 a.m. at 4400 Anderson Road at Hiram Clarke.

Houston Police Chief Troy Finner said in a press conference Friday that officers arrived to the scene “within minutes” following the call and once inside the school came upon the suspect “armed with a rifle” and he “surrendered without incident.”

Finner said Friday the suspect was a former student of the school. Police said Kelsey confessed to his role in the shooting and was subsequently charged.

“When he came to the building, the front door, the glass door, it was locked. He gained entry by shooting on the glass door and immediately fired upon one of the employees of the school,” Finner said.

The employee sustained a gunshot wound to the back. Police named the victim Saturday as school principal Eric Espinosa, 36, who was treated at a hospital and later released.

Police said Espinosa was alerted about the shooting and attempted to warn teachers and students.

“During the gunfire, one of the bullets struck the principal in his lower back. As the principal continued to help students and teachers flee the school, responding police officers arrived, located the suspect and arrested him without further incident,” Houston police said.

YES Prep Southwest Secondary said in a statement Friday that “no students have been injured.” The school serves grades 6 through 12.

Audio from a dispatch call reveals an official said: “I’m gonna need units at 4411 Anderson Rd, just got a message that there’s a man with a gun in the school.”

The Houston Fire Department initially told ABC News one person was transported to Memorial Hermann Texas Medical Center Emergency Room.

First responders were on the scene to actively clear the building, Houston Fire said after reports of the shooting.

A seventh grader who was evacuated from the school told ABC Houston station KTRK, “When I was coming out, I saw blood and glass shattering everywhere.”

“My teachers told me to stay back in the classroom where nobody can see you and officers came, saying, ‘Put your hands up. Go outside,’” the student said.

A staging area for parents was set up at West Fuqua and Hiram Clarke and students were sent to that location.

The students had gone through active shooter training just two days earlier. Finner commended students for remaining calm during the evacuation.

Finner said there are no other potential suspects and no further threat to the students.