Robert Gladden is the alleged gunman responsible for a shooting at Perry Hall High School in Baltimore, Maryland on Monday. Gladden, 15, left one victim in critical condition after he entered the school cafeteria around 10:45 a.m. and fired two gunshots.

According to multiple reports, students said that Gladden was being teased, so he left the cafeteria, came back in with the gun and fired off a round before he was grabbed by nearby guidance counselor Jesse Wasmer.

A second round was then fired before a school resource officer was able to arrest the 15-year-old, police said.

The 17-year-old injured student who reportedly had "special needs" was not suspected to be targeted by Gladeen. While officials haven't commented on Gladden's motive, they did say that he acted alone.

Gladden was taken into custody early Tuesday morning and charged as an adult with attempted first-degree murder and first-degree assault.

Gladden's reportedly took to Facebook before he went to school on Monday. Going by the name "Suicidal Smile," he posted "First day of school, last day of my life," just hours before he entered the building.

According to an NBC affiliate in Maryland, The teen's parents divorced two years ago. Gladdens father reportedly told the Associated Press that his son was bullied, and friends of the family agreed.

"We hung out when we were younger," one neighbor said. "They're all real nice people, always asking if we needed help with stuff. So, they were always good people."

Students at Perry Hall High School headed back to the classroom Tuesday, 24 hours after the shooting.