"(The driver of the truck) actually saw in the mirror he said that it was like hands and legs fly up in the air, so he immediately came to a complete stop and made a U-turn and went back to protect the scene," Chief Todd Scaldo said.
The two boys were flown to Arnold Palmer Hospital for Children in Orlando, where they are recovering.
"Out of 30-something years of doing this, it's the worst we've had of experiencing something like this. And like I said, our prayers and everything go to the family," Scaldo said.
Officials said the car involved stopped and the driver was cooperative with police.
The conditions of the children have not been released.
The investigation is ongoing.
A family friend said a GoFundMe account has been created to help the family with medical expenses.