A fired MTA bus driver hijacked an M101 on the Upper East Side on Tuesday morning and took it on a three-block joyride — even attempting to pick up passengers along the way, sources said.

Rogue former MTA worker Charita Headley, 34, boarded the bus, lit up a cigarette and started babbling in the back of the bus at around 7:10 a.m. near Third Avenue and East 97th Street, the sources said.

“They’re coming after me. They’re going to shoot me!” Headley ranted to the other passengers as she puffed away.

The driver told Headley several times to put out her butt and demanded she get off, but she refused.

He then radioed a supervisor to have a replacement bus meet them at the corner so the other passengers could be taken off and put on a new vehicle while authorities dealt with Headley.

As soon as he stopped the bus and got the puzzled passengers off, Headley — who was fired by the MTA in July for extended absences — allegedly hopped into the driver’s seat and began motoring up Third Avenue.

She even hearkened back to her good old days of picking up riders.

“The crazy lady manages to take off and pulls into the bus stop at 100th Street as if she’s going to pick up passengers,” an MTA union source said.

But as Headley made the pit stop, the replacement bus cut her off. An MTA worker then ran up to her bus, reached into the driver’s side window and pushed the hydraulic button, disabling it.

Headley was promptly taken into custody and transported to Metropolitan Hospital for psychiatric evaluation.

She was later charged with unauthorized use of a vehicle, according to police.

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