Kaela Archambault, 20, crossed the center line with her SUV and hit the school bus head-on, reports CBS affiliate KMOV in St. Louis.
The SUV was engulfed in flames and Archambault was pronounced dead at the scene. Ambulances and trucks from multiple fire houses responded.
A Rockwood School District spokesperson said five Geggie Elementary students were on the bus at the time of the accident. The students in grades 1, 2, 3 and 5 were all were taken to St. John's Mercy Medical Center for treatment and expected to be released.
The bus driver was treated at the hospital and released.
Archambault lives in Florida, but had been visiting family in the area, KMOV reported. Investigators have not said what may have caused her to cross the center line.
The accident took place around 8:30 a.m. Thursday.