The 16-year-old alleged gunman accused of killing three children and a teacher at Silver Rail Elementary School in Bend, Oregon, has been identified as John J. Griffin II, according to law enforcement officials cited by NBC News. The incident occurred on Thursday (October 16), when teenage suspect forced entry into the school by firing through locked doors just before 1 p.m. Pacific Time.

Police say the shooting ended when a bystander, identified by family members as 36-year-old Kaylub Giamanco, pursued and fatally shot Griffin inside the school. Giamanco, a carpenter and father of two students at Silver Rail Elementary, was driving home for lunch when he heard gunshots and saw the gunman entering the school. Giamanco has a concealed-weapon permit and decided to intervene after seeing the armed teenager, according to statements from his brother, Kyle Giamanco.

Griffin allegedly shot his way into the school’s special education classroom, where three children ages five, eight, and eleven, and a teacher were killed. Two others, a seven-year-old child and a 54-year-old teacher, were critically injured. Police arrived within minutes of the first 911 call but found the shooter already dead inside the building.

Law enforcement officials told NBC News that the firearm used in the attack was purchased by Griffin’s mother around his birthday in August. It remains unclear whether Griffin had any prior connection to Silver Rail Elementary School. The motive for the shooting is still under investigation, with Bend Police Chief Mike Krantz stating that the inquiry will continue over the coming days.

The community has responded with grief and support. At a candlelight vigil, Bend Mayor Melanie Kebler called it a “dark day in the city,” while Oregon Governor Tina Kotek expressed her heartbreak and thanked the bystander who intervened, stating, “Your actions carry a heavy emotional burden, and I just want you to know that my thoughts are with you, as well."