The van, thought to be affiliated to a church in Fort Pierce area, was returning from a trip to Fort Myers.
Eight adults, including the driver, died when the bus allegedly went through a stop sign before eventually stopping in a ditch.
Police are not releasing the details of the church involved until all next of kin has been informed.
It's thought the bus careered over four lanes on Highway 27 early this morning before eventually being stopped by the ditch.
The other 10 who were injured include a four year old girl who is said to be in a stable condition. Two are critically ill.
Lt Greg Bueno, Florida Highway Patrol, told reporters some of the passengers were wearing seatbelts and a full investigation was now underway.