It was previously believed there were two minivans. But the school says on its website Sunday that there were actually three vans carrying 26 students.
The university says the passengers in the lead van were unaware of the accident and proceeded to their destination.
Police say one of the vans drifted to the side of the road and then rolled when the driver tried to correct course.
Killed in the accident were Daniela Lekhno, of Manalapan, N.J.; Austin Brashears, of Huntington Beach, Calif.; and Roch Jauberty, whose parents live in Paris. A female student was critically injured.