Nearly 50 bus drivers in Cobb County called out sick Monday morning, leaving passengers stranded and spurring rumors the no-shows were a result of a silent protest from employees.

“I got like three of four customers saying the No. 40 and the No. 45 never showed up,” taxi driver Melvin Gordon told Channel 2 Action News. “The bus driver pulled off (and) told them they had to wait on another bus, which was probably about an hour.”

CobbLinc called in extra drivers to make up for the shortage that led to canceled services and delayed routes, Cobb County spokesman Ross Cavitt said in a news release. The transit system, which provides service for nearly 2.5 million passenger trips, has nearly 100 drivers.

“The system shuffled resources this morning to make sure Paratransit services were available for critical customers,” Cavitt said. “A majority of afternoon routes will run as scheduled.” Paratransit services were cancelled as a result, he said.

Paratransit service is a complementary curb to curb service for passengers who cannot ride the local fixed-route CobbLinc buses, according to CobbLinc's website. Passengers must be certified to use Paratransit service.

First Transit, the Ohio firm that operates the CobbLinc transit system, has been working “to compensate for missed routes,” spokesman Jay Brock said in an emailed statement.

First Transit does not know what caused the shortage or the number of routes or passengers affected by it, he said. Officials also said they had no advanced notice there would be a shortage.

“We regret that our customers experienced disruptions to their schedules due to the unexpected shortage of bus operators today,” CobbLinc Director Andrea Foard said. “We remain committed to providing quality, timely, and safe service to our customers and endeavor to assure similar disruptions do not occur in the future.”

Despite rumors of a silent protest, retired bus driver and union representative Ken Howell said it's likely an illness that led to dozens of call outs. The union is in the middle of a dispute with CobbLinc over bonuses, but Howell said the dispute is in mediation.

Buses are expected to run on a Saturday schedule Tuesday with the exception of Paratransit and Express Bus routes, Cavitt said.

Riders are asked to call 770-427-4444 or check the CobbLinc BusTime app and the CobbLinc website for route updates.

— Staff writer Meris Lutz contributed to this article.