KELLER (CBSDFW.COM) – A school bus company apologized after leaving a 10-year-old girl behind at school, even though school staff tried to stop the bus.

The girl’s father said he still had no explanation from the company for the incident.

David Hart said when his daughter Kailey made it to her bus Friday, the doors were closed and the bus driver started to leave.

“She waved at him and tried getting his attention,” Kailey said. “And he looked at her and then she asked him does she ride your bus and he said no.”

Keller ISD said a staff member had tried to stop the bus but couldn’t.

After the missed ride, the girl was instructed to use an office phone to call for a ride. School staff dialed her grandmother for her. Hart, who was out of town, said the girl was told to then wait outside for a ride, which was nearly an hour.

“When I pull up and there’s no adults around her, and she was outside of the school, I was not happy,” said the girl’s grandmother, Lisa Wilkerson.

There was no communication Hart said from the district or Durham School Services about the incident. Monday he said Durham told him it was investigating what happened.

Keller ISD said school staff were still on campus while the girl was waiting and that she could have waited in doors. The district acknowledged it was possible that staff who witnessed the bus leaving had not communicated the situation to staff inside. The district also said it was aware Durham was investigating.

The company told CBS 11, however, there is no investigation. A spokesman said the girl came out late, with a teacher, who waved at the bus but never had a conversation with the driver. The company said ideally the driver should have stopped and it has encouraged him to wait a few more minutes in the future to make sure all of his riders are present.

Hart said Monday night he was consulting with an attorney about the incident.