NEW YORK (CBSNewYork) — Passengers expressed frustration and confusion at the Port Authority Bus Terminal Monday afternoon after a shortage of drivers left several of them stranded since Sunday night.

“There were no buses between 11:30 last night and 7:30 this morning,” said passenger James Rodway.

A crowd of about 150 Greyhound passengers told CBS2’s Scott Rapoport that they’ve been waiting in long lines for their buses for hours and hours.

For some, the wait has been gone on from sundown to sunrise.

“Since 9:30 last night,” passenger Esther Anderson said.

Anderson and her family slept on a bench at the terminal overnight. Her bus to Charlotte, North Carolina, was dramatically delayed. She says it’s been a nightmare.

“We were waiting for almost six hours,” she said. “Then they didn’t have a driver. But there were eight buses sitting over there. No drivers.”

Passenger Jeremy Rodway was one of many people waiting to go to Atlantic City. He said he was told the same thing.

“The bus was delayed because the driver wasn’t available,” he said. “This is been going on too long.”

On Monday afternoon, Greyhound issued a statement addressing the delay and acknowledging the problem came from a lack of available legal drivers.

“We are currently experiencing delays at the Port Authority as we wait for drivers to become available once they complete their federally mandated rest,” said Greyhound’s statement. “We are working diligently to accommodate the increase in customers with the limited resources we have available, and expect to have everyone en route to their destinations soon.

“With resources as tight as they have been, any delay that occurs elsewhere can create a domino effect, which can have an impact on a drive’s hours of service,” it read. “We are also actively hiring drivers in order to meet the increasing demand for our service so these types of delays are minimized.”

The head of the Greyhound bus drivers’ union told CBS2 the delay was caused by equipment problems and a shortage of manpower. He says the delays were not the result of any job action on their part.