A Mississippi teenager was charged with possessing an explosive device after a homemade bomb turned up in a junior high school library, triggering an evacuation Wednesday, local media report.

A student at a different school alerted officials about the bomb at Warren Central Junior High in Vicksburg, Police Chief Walter Armstrong told WAPT-TV. Crews detonated the bomb, and nobody was hurt, according to Deputy Police Chief Robert Stewart.

The suspect also was charged with possessing weapons on school grounds, specifically knives, The Vicksburg Post reported. A second student also faces a knife charge, but police reportedly say they do not believe that person was involved in making or transporting the explosive.

Police were called after school security officers were alerted to the bomb, Stewart said, adding that a police dog detected possible explosives in a backpack in the school library.

A bomb squad from nearby Clinton retrieved the object with a robot and detonated it in a nearby field after 3 p.m. The FBI and the Bureau of Alcohol, Tobacco and Firearms also provided assistance.

Stewart said the device was "relatively small" and would have caused little or no damage.

On Wednesday evening, police questioned two male students, according to Stewart, who said cops do not believe anyone else was involved. Children 13 and older in Mississippi can be charged with adult crimes.

The school's 400 students were evacuated to neighboring Vicksburg Junior High and later sent home from there. "We always respond whether it's true or not," said Superintendent Chad Shealy.

The Associated Press contributed to this report.