OTTAWA -- More than 2,300 Ottawa students won’t be taking their regular school buses on Monday due to a “severe driver shortage.”

The shortage amounts to more than 100 drivers out of 555 yellow bus routes, the Ottawa Student Transportation Authority said in a presentation Friday.

“We’re sort of deeply horrified by the situation that we’re in, but it can’t be helped,” OSTA general manager Vicky Kyriaco said Friday.

OSTA says 30 routes have been cancelled for Monday, the day school bus service is set to resume. Forty-five schools are affected by the cancellations.

The authority says 2,360 students will not receive transportation services until more drivers become available.

"There’s not enough spare drivers to cover all of the open routes,” Kyriaco said.

OSTA provides transportation for students in the Ottawa-Carleton District School Board and Ottawa Catholic School Board.

The list of schools and cancelled routes will be posted online and updated daily by noon. OSTA says there may be cancellations on short notice every morning.

OSTA has reconfigured 146 routes to bus routes due to the shortage, extending some, changing timings and stops, and other changes.

However, OSTA said it doesn’t want to exacerbate the shortage by making changes that are unacceptable to drivers.

“Changes to one route can impact five or more other routes, and each change must be communicated and agreed upon,” OSTA’s presentation said.

Some students from Grades 7 to 12 have also been shifted to OC Transpo. Seven buses have been redeployed from Notre Dame High School, with one each from Holy Trinity High School and Earl of March Secondary School.

OSTA also says it’s in discussion with coach service to possibly provide more buses.

The driver shortage is due to drivers’ concern about their health and their family’s health. Many of the drivers opting out are over 60 and more vulnerable to severe symptoms if they catch COVID-19.

There is also a historical shortage of drivers due to changes in the labour market creating fewer retirees.

OSTA says some drivers are waiting to see how the return to school goes before possibly coming back in October or November. However, there is a “strong possibility” the shortage will continue.

Efforts are being made to keep drivers as safe as possible, including personal protective equipment and hand sanitizer, mask-wearing for students, seat assignments and enhanced cleaning.

- With files from CTV News Ottawa's Jeremie Charron