The chief of police for the Dallas Independent School District says the student who shot four students when he opened fire at a Dallas high school this week was in and out of the building in less than two minutes and is believed to have been targeting a specific student.

Five students were injured in a shooting Tuesday afternoon at Wilmer-Hutchins High School in southeast Dallas when a 17-year-old allegedly snuck into the school and fired “indiscriminately,” according to a state affidavit for the suspect’s arrest warrant.