Gov. Greg Abbott responded to a mass shooting at a school in Arlington, Texas, on Wednesday, saying the alleged gunman possessed the gun illegally. Timothy George Simpkins, an 18-year-old student at Timberview High School in Arlington, was charged with three counts of aggravated assault with a deadly weapon. He turned himself in to police hours after the incident unfolded, police said. Three of the four victims were hospitalized, including a 15-year-old boy in critical condition, a 25-year-old man who was shot and is in good condition, and a teenage girl who suffered minor injuries and has since been released, officials said. Abbott, a Republican, addressed the shooting Wednesday while police were still searching for Simpkins. Abbott told reporters that “under Texas law, it is illegal for the shooter to possess or have purchased the gun that was used in … [the] crime,” before saying that the shooter possessed the gun “illegally.” …