It happened around 11:39 a.m. at Glasgow High School on S College Avenue in Newark.
Delaware State Police were called in to break up the fight.
"The SRO and school staff members broke up the initial fight, but then the group separated in four separate smaller groups and continued actively fighting throughout the hallways," said police in a news release.
Nine students were taken into custody.
Police say two 17-year-old females were charged with inciting a riot and other related offenses.
Seven other students were issued a summons for disorderly conduct.
According to police, one of the teens was in possession of a Taser.
One student sustained lacerations to the face as a result of the fight.