The accident happened in the westbound lanes of the highway at milepost 303 in West Nantmeal Township, Pa. shortly after 4 p.m. Monday, Pa. State Police said.
The white minivan went airborne and landed on its roof, leaving clothing and other belongings strewn across the highway.
A 5-year-old boy was killed in the crash. Seven other passengers were rushed to area hospitals with serious injuries, police said. Some were taken via a medevac helicopter.
The names of those involved in the accident have not yet been released.
It's unclear what caused the car to overturn, but there was only one vehicle involved in the accident.
The westbound lanes of the highway were closed for several hours as police investigated and cleaned up the crash. The highway was reopened around 8 p.m.