A 13-year-old Northwest Middle School student fatally shot his brother Tuesday evening, authorities said.

Officials initially thought the 12-year-old boy died of a self-inflicted gunshot wound around 7:15 p.m. in his bedroom, but further investigation found that his brother shot him.

The brother, who is being held at the Richard L. Bean Juvenile Detention Center, was charged with first-degree murder. He has a detention hearing set for Thursday.

Attorney Gregory P. Isaacs, who is representing the alleged shooter, said he couldn't comment  on the issue because his client is a juvenile. He did say, however, that he will ask the judge "to impose a gag order" on the case.

Knoxville police said little about the investigation, but that the brothers were the only ones home at their Needham Lane residence. Knoxville Police Chief David Rausch confirmed a phone call was made from the home to the parents, who contacted police.

Rausch said he cannot release the names of the victim or the brother charged because each boy is younger than 18. Both boys attended Northwest Middle School.

“Unfortunately, in our community three years in a row right before Christmas we’ve suffered the loss young people to a tragedy," Rausch said. "This is unfortunately something that’s becoming something that is all too common. Our hope is that as a community we can come together, and try to figure out solutions to deal with these horrible tragedies, and stop putting small children in graves.”

Counselors will be available Wednesday at Northwest Middle School for the students.

“We are deeply saddened by the tragic event that occurred Tuesday night involving two of our students,” said Karen Loy, principal of Northwest Middle School. “Our hearts are heavy as we offer our thoughts and prayers to the family during this very difficult time.”

Rausch thanked investigator Tom Thurman for leading the case, and called his work "astounding."

"Looking at this case, I won't go into details, but can tell you it appeared very complicated," Rausch said. "I told you at first it (the gunshot wound) appeared to be self-inflicted.

"Our thoughts, our prayers go out to the family," he added.

The investigation is ongoing.

Zaevion Dobson, a former Fulton High School football player, died last December while shielding several of his friends from gang-related gunfire.

Two years ago, two Sunnyview Primary School students and a teacher’s aide were killed when one Knox County school bus collided into another.