Dozens of D.C. students arrived at their schools before dawn Thursday for a long-awaited ski trip to a Pennsylvania mountain. But the buses hired for the trip never showed because of a payment dispute between the school system and the bus company.

School system officials acknowledge that they owe the bus company, Capital Entertainment Services, about $430,000 for services provided during the past two years. But D.C. schools officials said that the bus company violated its current contract with the school system to provide services this year by not showing up for the ski trip Thursday.

“There is money owed to this company from previous years and we will work that out, and we intend to do right by the company,” said schools spokeswoman Melissa Salmanowitz. “But the fact that our students suffered because this person decided not fulfill their contractual obligations is unacceptable.”

Deputy Schools Chancellor Lisa Ruda said it is unfortunate that a disagreement among adults ended up affecting students.

“Today was a serious breach of trust and we fell down, the collective we fell down, in how we serve our children,” Ruda said. “All I know how to do is to own the mistake, apologize for it and then do my darnedest and make sure it doesn’t happen again.”

Capital Entertainment Services did not respond to a request for comment Thursday.

Five schools were slated to take students on the ski trip as part of an effort to expose city children to a new sport.

Two schools were able to find replacement buses to salvage the trip. But three schools had to cancel, leaving parents frustrated and children — many of whom were looking forward to their first-ever ski experience — disappointed.

“Thumbs up to DCPS for getting kids to try something like this, something totally outside their environment,” said Gina Arlotto, the mother of a sixth-grader at Stuart-Hobson Middle School whose trip was canceled. “But when you can’t rely on a system to come through for children . . . my head is about to explode when stuff like this happens, that’s how angry I get.”

Other parents said that Thursday’s bus fiasco is a symptom of a broader problem: A lack of support for student athletics in the city’s school system.

In a letter to parents, Ruda said that the school system would help reschedule the ski trips and would ensure that families did not lose money because of Thursday’s cancellation. Students paid $75 each for the trip, a fee that included transportation, equipment, lift passes and lessons.

“I know how much these trips mean to our students. In many cases, these trips offer a chance for young students to learn a new sport, receive a reward for their efforts in the classroom, or enrich their academic lives,” Ruda wrote. “I want to assure you that we are very sorry for this mistake and will do whatever we can to ensure that this does not occur again.”