The teen was identified as Peyton Ham, 16.
No suspects have been arrested yet.
Texas Governor Gregg Abbott said that a state trooper was among those hurt in the shooting and said the state would assist in prosecution of the gunman.
While surprising and seemingly isolated, the incident is one of several regarding the easy confusion of toy guns and real guns.
He was attacked last week by two suspects who stole his gun and were later arrested.
The soldier's gun was stolen around Shfaram in the early hours of Thursday morning by two assailants.
The NRA in recent decades has been one of the leading voices opposing proposed or existing gun control measures.
A man allegedly told acquaintances that he wanted to kill House Speaker Nancy Pelosi, and travelled to DC with a rifle and hundreds of rounds of ammunition.
"We have the scene secure and a person of interest in custody," Rockford's police chief Dan O'Shea said.