ARLINGTON, Texas (KXAN) — Police in Arlington, Texas, say four people were injured in a shooting at Timberview High School Wednesday morning — and a student was arrested in connection with the incident.

The student suspect has been identified as Timothy George Simpkins, 18, who authorities spent the minutes after the shooting searching for. Arlington Police reported Simpkins was arrested Wednesday afternoon and charged with multiple counts of aggravated assault with a deadly weapon.

An arrest affidavit for Simpkins said the incident began as a fight between Simpkins and another student. A witness account described in the affidavit said after the fight was broken up by several people, Simpkins reached into an orange backpack, grabbed the gun and started shooting.

Police report three of the victims were Timberview students and another was a teacher. One of the victims was pregnant.

NBC Dallas-Fort Worth reports Mansfield Independent School District sent a letter to families, explaining students and staff were locked inside classrooms and offices at Timberview High School while Arlington, Grand Prairie and other police crews searched the scene.

In a press conference Wednesday, ATF Special Agent Jeffrey C. Boshek II explained his personal connection with incident, saying: “As a law enforcement officer and then as a parent of a student in Arlington ISD this is kind of your scariest moment not only what you do for your job but when you have a wife who’s a teacher here and several kids who go to school in the district.”

Gov. Greg Abbott said in a statement Wednesday:

“As law enforcement continues their investigation, our hearts go out to the victims of this senseless act of violence. Thank you to the law enforcement officers and first responders who arrived on the scene to help the victims and prevent further violence. I have spoken with the Mayor of Arlington and offered any assistance the state can provide, and I have directed the Texas Department of Public Safety to make state resources available to help bring the criminal to justice. I ask all Texans to join Cecilia and me in praying for the victims, their families, and the entire Timberview High School community.”

Governor Greg Abbott

Simpkins has since bonded out of Tarrant County Jail, according to jail records. His bond was set at $25,000 for each of three aggravated assault charges, according to the affidavit.