The stepfather of the Maryland teen accused of opening fire on a classmate during the first day of school was arrested Tuesday on drug and weapons charges.

Police arrested Andrew E. Piper, 43, for marijuana and illegal firearm possession during a visit to the home of alleged Perry Hall High School shooter Robert Wayne Gladden, Patch reports.

On Monday, the 15-year-old Gladden brought a disassembled shotgun, 21 rounds of ammunition and a bottle of vodka to school, police say.

After second period, he allegedly fired one round into a fellow student's back before teachers subdued him as a second round struck the ceiling.

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Authorities announced that Gladden will be charged as an adult for attempted first degree murder and assault.

The weapon used in the school shooting did not belong to Piper and his charges are not related to the incident. Police say that Gladden took the shotgun from his father's home, CBS Baltimore reports.

Gladden is believed to have planned the attack, police say, according to ABC.

When asked about the shooting, the boy's father said his son was the victim of bullying.

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  • Robert Wayne Gladden Jr

    This booking photo made available by the Baltimore County Police Department, shows Robert Wayne Gladden, Jr., 15, of Baltimore. Gladden, Jr. was charged as an adult with attempted first degree murder and first degree assault in the shooting of a classmate on the first day of school at a Baltimore high school. (AP Photo/ Baltimore County Police Department)

  • Andrew Piper

    This Aug. 28, 2012 photo provided by the Baltimore County Police Department shows Andrew Piper of Baltimore. Piper is the stepfather of Robert Wayne Gladden, Jr, who was charged as an adult with attempted first degree murder and first degree assault in the shooting of a classmate on the first day of school at a Baltimore high school. Piper was arrested on charges unrelated to the shooting. He was charged with illegal possession of weapons and drugs at his home. (AP Photo/ Baltimore County Police Department)

  • Robert Gladden

    Profile picture from Robert Gladden's Facebook page

  • Robert Gladden

    Profile picture from Robert Gladden's Facebook page

  • Robert Gladden

    Profile picture from Robert Gladden's Facebook page

  • Tracie Bradford, of Perry Hall, Md., consoles her daughter Leah, a student at Perry Hall High School who says she was in the school's cafeteria when a student was shot there and critically wounded on the first day of classes, Monday, Aug. 27, 2012, in Perry Hall, Md. A suspect was taken into custody shortly after the shooting, according to police. No one else was reported injured. (AP Photo/Steve Ruark)

  • Parents gather at Ebenezer Road outside Perry Hall Middle School. Several had been notified by their children that a shooting happened at the nearby high school. <a href="http://perryhall.patch.com/articles/breaking-shooting-at-perry-hall-high-school" target="_hplink">Credit: Patch</a>

  • From left: Sarah Erpenstein and Carol Erpenstein. Sarah Erpenstein told Patch that she was in the cafeteria at the time of the shooting. <a href="http://perryhall.patch.com/articles/breaking-shooting-at-perry-hall-high-school" target="_hplink">Credit: Patch</a>

  • Students continue to file out of Perry Hall High School Monday afternoon following a shooting Monday morning. <a href="http://perryhall.patch.com/articles/breaking-shooting-at-perry-hall-high-school" target="_hplink">Credit: Patch</a>

  • Parents gather at Ebenezer Road outside Perry Hall Middle School. Several had been notified by their children that a shooting happened at the nearby high school. <a href="http://perryhall.patch.com/articles/breaking-shooting-at-perry-hall-high-school" target="_hplink">Credit: Patch</a>

  • Parents gather at Ebenezer Road outside Perry Hall Middle School. Several had been notified by their children that a shooting happened at the nearby high school. <a href="http://perryhall.patch.com/articles/breaking-shooting-at-perry-hall-high-school" target="_hplink">Credit: Patch</a>

  • Parents and students try to reunite after a student was shot and critically wounded on the first day of classes at Perry Hall High School, Monday, Aug. 27, 2012, in Perry Hall, Md. A suspect was taken into custody shortly after the shooting, according to police. No one else was reported injured. (AP Photo/Steve Ruark)

  • Becky Hobgood tries to locate her daughter after a student was shot and critically wounded on the first day of classes Perry Hall High School, Monday, Aug. 27, 2012, in Perry Hall, Md. A suspect was taken into custody shortly after the shooting, according to police. No one else was reported injured. (AP Photo/Steve Ruark)

  • Students evacuate Perry Hall High School after a student was shot and critically wounded on the first day of classes Monday, Aug. 27, 2012, in Perry Hall, Md. A suspect was taken into custody shortly after the shooting, according to police. No one else was reported injured. (AP Photo/Steve Ruark)

  • Parents wait to reunite with their children after a student was shot and critically wounded on the first day of classes at Perry Hall High School, Monday, Aug. 27, 2012, in Perry Hall, Md. A suspect was taken into custody shortly after the shooting, according to police. No one else was reported injured. (AP Photo/Steve Ruark)

  • Parents and students try to find each other after a student was shot and critically wounded on the first day of classes at Perry Hall High School Monday, Aug. 27, 2012, in Perry Hall, Md. A suspect was taken into custody shortly after the shooting, according to police. No one else was reported injured. (AP Photo/Steve Ruark)

  • A Baltimore County police officer speaks to a parent as students are evacuated from Perry Hall High School after a student was shot and critically wounded on the first day of classes Monday, Aug. 27, 2012, in Perry Hall, Md. A suspect was taken into custody shortly after the shooting, according to police. No one else was reported injured. (AP Photo/Steve Ruark)

  • Parents and students try to reunite after a student was shot and critically wounded on the first day of classes at Perry Hall High School, Monday, Aug. 27, 2012, in Perry Hall, Md. A suspect was taken into custody shortly after the shooting, according to police. No one else was reported injured. (AP Photo/Steve Ruark)

  • Tracie Bradford, Leah Bradford

    Tracie Bradford, of Perry Hall, Md., consoles her daughter Leah, a student at Perry Hall High School who says she was in the school's cafeteria when a student was shot there and critically wounded on the first day of classes, Monday, Aug. 27, 2012, in Perry Hall, Md. A suspect was taken into custody shortly after the shooting, according to police. No one else was reported injured. (AP Photo/Steve Ruark)