WORCESTER, Mass. — Parents of Worcester special needs students are angry after experiencing a scare Friday when their children’s bus ride home from school took hours longer than usual.

One woman who said her autistic son, who is in kindergarten, did not get home until after 8 p.m.

According to state regulations, special needs students are not supposed to be on the bus for more than an hour.

“Angry isn’t even the word. I was devastated,” said parent Jen Lynn.

“(I) was freaking out on the bus when he got home,” said parent Sophie Ewings.

The children are students at Nelson Place Elementary. Some of them are nonverbal and have serious medical issues.

“Every child on that bus was put into a situation that was really dangerous,” said parent Leah Corbin.

Corbin told WCVB that her daughter was sitting in her own urine and suffering an asthma attack when she finally tracked her down.

“They had no idea that she was wheezing that bad,” Corbin said. “If you know anyone with asthma, then you know that it can be life-threatening.”

Many parents said they were not able to contact the bus company or the school department regarding their kids’ whereabouts.

“The bus company was closed,” said parent Jonathan Mastropoll. “(There was) no answer.”

“By 6:30, quarter of 7, I had to call the Worcester police because I didn’t know where my kid was,” Lynn said.

A spokesman with the bus company confirmed that some of the bus routes ran late on Friday and that the company did receive calls from concerned parents and guardians.

Edward P. Flavin, director of communications for National Express LLC, released the following statement to WCVB:

“While the delays were unacceptable, there were a couple of reasons that caused these delays. Several school staff members who regularly assist with routes were not at school as expected on Friday, and were filled in by substitute staff members. Some students did not have their name tags displayed on their backpacks, and some of our clients are non-verbal, so not having the same staff faces in place can make a difference.

“Also, some of the 18 passengers that you refer to were at Safe Haven — a designated safe area provided by and staffed by Worcester Public Schools — until we had all of their proper identification aligned with their routes before boarding their buses.

“We made an administrative error pertaining to routing on our end, and we apologize for the inconvenience this caused for our passengers, parents, and guardians … the safety of our students is our number one priority, and we have made adjustments to ensure that we have the proper procedures in place to prevent this from occurring in the future.”

Worcester Public Schools Maureen Binienda said the students usual bus driver called out sick. She acknowledged that the school district needs to improve its communication, which she hopes will be improved with a new tracking app that debuts next month.

“The whole event was upsetting to us and we’re going to make sure that it doesn’t happen again,” Binienda said. “It’s important that (the parents) know that we are upset also.”

Binienda and officials with the bus company met with parents Friday evening. Parents told WCVB that Binienda promised them a new plan by Friday.