(KCEN) -- It's a parent's worst nightmare that came true for a southeast Texas family.
Their toddler was hit and killed by a school bus after running into the street.
It happened Tuesday afternoon in Chapel Hill.
That's where police say a mother crossed the street in front of a stopped bus and didn't realize her daughter had followed her into the road.
But the bus moved forward, hitting the 18-month-old girl.
One witness says they chased the bus down, but not before it had traveled about 75 feet.