A Round Lake area girl who was traveling to Disney World was killed in a traffic accident when the family's minivan was struck by an RV pulling a horse trailer, officials said.

Gwendolyn McCormick, 4, died Nov. 11 at the Riley Hospital for Children in Indianapolis while being treated for injuries suffered in the Nov. 6 accident on Interstate 65, Indiana State Police said.

Her 2-year-old brother, Quintin McCormick, suffered head injuries and also was treated at Riley Hospital. Officials said the boy is expected to recover and has been transferred to Illinois.

Officials said the accident took place at 5:40 p.m. when the family's Honda Odyssey was hit from behind by an RV that was pulling a horse trailer.

The RV driver, 72-year-old Charles Walker, told police officers that traffic in front of him came to an abrupt stop and he inadvertently hit the accelerator instead of the brake. The RV slammed into the minivan, pushing the van forward and causing a chain-reaction collision that involved four other vehicles.

The family was driving though Indiana, heading to Disney World in Orlando, Fla., officials said.

The childrens' mother, 36-year-old Erin McCormick, was taken to Wishard Hospital in Indianapolis and later released. Their father, Erik McCormick, was not injured in the crash, officials said.

Walker was ticketed for driving a vehicle in the third lane of the interstate while towing a trailer in violation of postings, driving a vehicle-trailer combination in violation of maximum length, and speeding when required to reduce speed.

Additional charges are not expected, police officials said.