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As events unfolded inside the school, A member of the Lubbock Fire Marshal’s Office, Lt. Elliot Eldredge, was en route to the apartment complex when he passed the school and noticed several people crouched outside.

Eldredge said he stopped and people told him a suspect was inside the school with hostages.
....
The fire department lieutenant said Bradley came out of the building once, but went back inside.

Later, Bradley came back outside but with the knife. Eldredge took the suspect into custody.

Lubbock police arrived seconds later.