TULSA, Oklahoma - Tulsa Transit suspended six bus drivers late Monday and fired them today, accusing them of embezzlement.

The city doesn't have much to say about the investigation, but multiple sources tell us some drivers were printing out bus passes, selling them on the side at half price and pocketing the money.

Several drivers caught up in the scandal are long-time employees of the city.

Tulsa Transit rides average under two dollars, but there's an underground system where rides come at less than half that price.

Almost every rider we spoke with said they've been offered discount passes they figured must be bogus.

One man said he's bought them several times.

"$2. I paid $2, and you know what, it was a bargain," he said.

Multiple sources tell News On 6 that Tulsa Transit discovered drivers were printing out extra "courtesy passes" usually given out when the bus is late or breaks down.

The sources described a system of passes sold by a third party, with drivers getting a cut of the money.

When the scandal was discovered, Tulsa Transit identified six drivers it believes are involved.

Three were arrested and booked into jail: Justin Copeland, Lawrence Morgan and Kenneth Speed.

Copeland was featured in this driver recruiting commercial for Tulsa Transit, talking about the good pay and excellent fringe benefits.

He's one of the most experienced drivers working for MTTA.

According to the city, three other drivers were fired, but not arrested, because they paid back the amount that was taken.

The passes are printed out through the fare box on each bus, at the driver's discretion.

Because so many of the passes are in circulation, and MTTA isn't sure how many are legitimate, sources say the bus service plans to invalidate the outstanding passes.

The city of Tulsa will only say, "MTTA has taken measures to ensure this type of theft will not occur in the future by disabling a certain functionality in the fare box system."

Frequent bus riders say the discount passes sold on the street are nothing new - they say it's been happening for years.

"Up here at the bus station, selling them right here? Uh-huh," she said.

We asked the city to tell us why the drivers weren't all arrested, and how much a driver can steal and avoid arrest just by paying it back.

The City of Tulsa said, “MTTA agreed to not press charges for the drivers if they paid the amount that was taken. The other three drivers did not accept this offer and were booked into jail.”