Two people died on impact in Tuesday evening's school bus accident on I-79 near Route 422 in northern Butler County.
The victims include 14-year-old girl and a 31-year-old bus driver.
Several other students are hospitalized with moderate to severe injuries.
The bus transporting students from Lincoln Park Performing Arts Charter School in Midland, Beaver County struck the back of a box truck.
I-79 was closed in the area of the crash for several hours.