The shooting and subsequent hostage drama came as a national debate rages over gun violence, especially in schools, after a gunman shot dead 20 students and six staff members at a Connecticut elementary school last month.
In Alabama on Wednesday night, the suspected gunman remained holed up with the boy in the underground bunker on his property down a dirt road. Any efforts to negotiate with the man, or to stage a hostage rescue operation, were shrouded in secrecy with authorities declining to comment.
Television images showed security force officers, clad in camouflage uniforms and brandishing assault rifles, patrolling the area.
An Alabama legislator, Representative Steve Clouse, told reporters the hostage suffered from Asperger's Syndrome and ADHD but had apparently been able to receive his medication while held captive. The Dale County Sheriff's Department said the child was not believed to have been harmed.
Schools in the area of the Alabama shooting were closed on Wednesday and will remain shuttered for the rest of the week.
Dale County Superintendent Donny Bynum lauded Poland as "a hero ... who gave his life to protect 21 students who are now home safely with their families."
The superintendent's assistant said the young boy still being held by the gunman appeared to have been chosen at random.
"Emotions are high, and it's a struggle for us all to make sense of something so senseless, but let us keep this young student, his family and Mr. Poland's family in our thoughts and prayers," Bynum said in a statement.