LOUISVILLE, Ky. (AP) — Kentucky’s largest school system cancelled the second and third day of classes after a disastrous overhaul of the transportation system that left some children on buses until just before 10 p.m. on opening day.

Jefferson County Public Schools Superintendent Marty Pollio called it a “transportation disaster” in a video posted on social media Thursday morning. Pollio apologized to the district’s 96,000 students along with their families, the bus drivers, and the school officials who had to stay with students for hours as they waited on buses to arrive Wednesday.

He called the decision to close schools on Thursday and Friday the most difficult of his career but said it was necessary. District officials will spend the four days before Monday reviewing the routes and having drivers practice them, he said. The district that encompasses Louisville has 65,000 bus riders, according to its website.

The disaster came after major changes to school bus routes and school start times this year meant to alleviate a bus driver shortage, the Courier Journal reported. The district spent $199,000 to hire the AlphaRoute engineering firm to create a plan that would cut the number of bus routes and stops.

In pushing for the changes, Pollio said the district simply could not keep up with its current routes because of the driver shortage. Even after increasing pay and cutting routes, the district did not have enough drivers, and students continued to get to school late and leave school late all year long, he said.

The district opened an online comment form for the new bus routes on July 24 and received thousands of complaints from parents concerned that their children were having to walk too far to catch the bus or that bus stops were at at busy, unsafe intersections. District spokesperson Mark Hebert told the paper last week that they were continuing to review the parent requests for changes.

Latasha Gomis told the paper last week that the bus for her two elementary school children was scheduled to pick them up at 6 a.m. for a 7:40 a.m. school start. The bus stop is almost a half-mile from their home and there are no sidewalks.

Gomis called the district’s transportation department but was told nothing could be changed, she said. Kentucky law allows bus stops for elementary students to be up to a half-mile away while middle and high school students may walk up to one mile.