After a bomb-sniffing canine confirmed the explosive was real, bomb techs disarmed the device, which police said could have caused "significant injury or death".
The department noted that "it was also determined that the male had been researching information and expressing interest in ISIS and promoting the organization".
Officials evacuated Nathan Hale High School Monday, according to Tulsa police. One student who looked at the backpack said he thought it looked like a box of matches. He said a friend immediately went to notify the school resource office. "She heard from her daughter, but I hadn't heard from my son, so I left work and came over".
The school was evacuated and the student was later arrested.
The suspect was charged with manufacture, possession, sale, use or attempted use of a weapon of mass destruction prohibited, the department said.More news: Opioid overdoses sending more people to ERs, especially in Pennsylvania, Delaware
This investigation is ongoing and criminal charges are pending. "He had a hat on really low covering his face nearly", said Olivia Jones, a senior at the school.
Riviere said there are no other threats to students. "They were kind of aggressive with him and brought him up to the top of the stadium and they were like patting him down and searching him and stuff, and he actually ended up being the suspect".
The juvenile male has been arrested but not identified publicly. "Threats against schools are treated very seriously and students who are determined to have made such threats face consequences through our school's code of conduct, as well as potential legal consequences".
That happened on February 15, a day after a mass shooting at a school in Florida.
No injuries were reported as a result of the incident.
"We have zero tolerance for this type of behavior, and we will not allow it in our schools", Sheriff Rick Staly said.