It happened at the William Allen High School around 11:00 a.m.
The victims are a boy and a girl, who were both slashed with a knife.
The suspect was later arrested off school grounds.
The school was placed on lockdown shortly after it happened.
Oustide the school worried parents gathered, but they could not get any clear answers. Police would only say two students were assaulted by a third student in a lower hallway in the school's annex building.
One parent, Denise Jamison, claimed her son was the initial target and it was his friends who were slashed. She said the suspect hit her son with a fist and his friends, a boy and a girl, came to his aid. She said they were the victims who were slashed.
Jamison said the school has been slow to react to her claims of simmering violence.
"They're not taking it serious. I'm afraid a child's going to die here," she said.
Police would not confirm that claim, saying they are still investigating.
