The Des Moines bus driver suffered a medical emergency while on his route.
The bus was stopped at the corner of Southeast 20th Street and East King Avenue a little before 7 a.m. Wednesday when the 55-year-old suffered a medical emergency.
Officers say children left through the back door of the bus and climbed into another bus while someone performed chest compressions on the driver.
The driver was pronounced dead at a hospital. His name hasn't been released.