LOUISVILLE, Ky. (AP) — Students in Louisville’s public school district will return to class starting Friday as part of a staggered reopening that stretches into next week, as administrators reboot a new bus schedule after the system melted down on the first day of school, the superintendent announced Monday.

Schools will reopen on Friday for elementary and middle school students, while high school students will return next Monday, Superintendent Marty Pollio said.

The superintendent apologized to staff, parents, bus drivers and students. “Even if they didn’t have a bus problem, I know we’ve inconvenienced a lot of kids and families who wanted to be right back in school, and we apologize for that,” Pollio said. “This was not anticipated, and that’s a mistake on me and on us.”

The revised schedule means students in Jefferson County Public Schools will miss more than a week of school since the disastrous opening day last Wednesday, when some students didn’t get picked up in the morning or came home hours late — with some arriving after dark. The fiasco resulted in hungry and tired children, angry parents and exasperated politicians.

Kentucky’s largest district, with 96,000 students, had retooled its bus system through a Massachusetts-based consulting company that uses computer algorithms to map out courses and stops. It was a response to a chronic bus driver shortage. The redesigned plan reduced the number of routes.

Pollio said last week that the district should have anticipated that the new plan didn’t leave enough time for buses to get from stop to stop, and to transport its 65,000 riders.

Some state lawmakers are now calling for evaluations of the school district map to decide whether it should be split up.

Many other districts across the country are also experiencing bus driver shortages.