Instead, the driver told police, he wanted to berate her for dropping off his child at a grandparent's house.

The 50-year-old driver, Leticia Lopez, told police that she had driven all but two Fontenelle Elementary students to their homes on Thursday when she discovered that one of her last two passengers' parents were not home.

So Lopez took the second student home first, then returned with the other student to see whether the child's parents had arrived. They hadn't, so Lopez took the student to a grandmother's home, five houses away. Lopez then headed back to the bus depot.

Along the way, Lopez told police, she noticed a white pickup driving erratically behind her. Lopez said she pulled over to let the truck pass, but the pickup swerved in front of her to cut her off and stopped.

Lopez told police that a man got out of the pickup, climbed up to her driver's side window and began yelling.

Lopez said the man began screaming questions about where his child had been dropped off -- the one she had tried to drop off twice. Lopez said she tried to answer, but the man interrupted with such statements as: "Shut up, or I'll bust your face."

According to police, the man grabbed Lopez by the shirt when she tried to radio for assistance, then hopped off the bus to stomp around the street and yell epithets at her. He then got in his pickup truck and drove to the grandmother's house.

Children can be left at another adult's home if parents fill out the appropriate paperwork, Omaha Public Schools officials said. Officials were investigating whether the driver followed procedures.

Police said they were continuing to investigate the alleged assault.