An investigation is underway after an Academy of Information Technology and Engineering student allegedly brought a weapon on a school bus Wednesday in Stamford.

Faculty members say that just before 2:30 p.m., a 16-year-old student shoved a girl and then whipped out a 4-inch knife.

A student who says he was one seat over when this happened says about 25 to 30 kids were on the bus at the time. No one was hurt.

School officials say they immediately called police, who had the student arrested the following morning before school started. They say the knife allegedly used to threaten his fellow classmate was found on the student during the arrest.

Police say they are unsure of a motive.

The student is not being named at this time, but News 12 has learned that he was expelled from school and is currently being detained in Bridgeport.

Students at AITE say they never would have expected something like this to happen. They say the student who was arrested is known to joke around but that no one has ever seen him threatening a classmate.