A 17-year-old Harker Heights High School student was arrested Monday in connection with the Austin Sixth Street mass shooting that left one man dead and 13 injured, according to the Killeen Independent School District.

The unnamed teenager is charged with aggravated assault as an adult under Texas law; another suspect arrested earlier is a juvenile, according to the Austin American-Statesman.

“The Killeen Independent School District and Killeen ISD Police Department are diligently working with Austin Police Department to assist in an ongoing investigation,” Killeen ISD spokeswoman Taina Maya said in a news release Monday. “As part of a joint effort, KISD Police arrested a 17-year-old male at Harker Heights High School earlier today. Killeen ISD will continue to assist law enforcement agencies to bring justice to the tragic events as quickly as possible.”