OSCEOLA COUNTY, Fla. -- A three-year-old student was forgotten on an Osceola County bus for nearly half the school day.

The bus driver is on unpaid leave and a part-time bus attendant has been fired. Transportation managers are calling it an “unfortunate mistake.”

Lidonte White was found Thursday wandering around the bus depot parking lot.

“Here I am, don't know where my baby is,” said his grandmother, Sandra Miller. “On the bus and they didn't get him off.”

Miller said she put her grandson on school bus number 17 Thursday morning for the ride to Mill Creek Elementary where he's enrolled in the pre-kindergarten special needs program. But he never showed up in class. That prompted a call from the school and putting Miller into panic mode.

Officials said Lidonte fell asleep aboard the bus and was missed by both the driver and an attendant after the other kids got off. Because it was a special needs bus, Lidonte was strapped in. And when he fell asleep, instead of toppling into the aisle, he just disappeared from view.

Bus managers say the video told the story of the driver's mistake.

A mechanic found Lidonte wandering around the parking area about 11:00am Thursday morning and handed the child off to his frantic grandmother who had just arrived at the bus yard.

“He had dried up blood on his nose. Dried up tears on his face,” said Miller.

The school district's investigation includes a look at the video from the bus. Managers are promising refresher training for drivers.

The Department of Children and Families is looking into the case. Lidonte was not harmed.