MUNHALL, Pa. -- Police say a Steel Valley High School student was injured in a fight on campus Wednesday morning.

Channel 4 Action News reporter Kelly Frey said that four students were involved in the fight.

The students started fighting over the Thanksgiving holiday, Frey said, and the fight started up again shortly before 8 a.m.

One student was taken to the hospital with a puncture wound, which is believed to be from a pen or a pencil, Frey said.

According to the superintendent, the object used to injure the student has not been found.

That student has been released from the hospital.

According to Frey, all four students -- ages 16, 17, 18 and 19 -- have been suspended.

Three students were taken to the Munhall Police Department.

The 19-year-old and the 18-year-old will be charged as adults, police said.

Police also said that the two younger students will be charged as minors.

All four students are facing charges of simple assault and reckless endangerment.