An MTA bus driver was robbed at knifepoint in East Harlem early Friday morning, police said. 

The driver, a 30-year-old woman, told police that a man boarded the bus at about 3 a.m. at 125th Street and Second Avenue without paying a fare. When the bus arrived at the next stop at 119th Street, he displayed a knife and demanded money. 

A Transport Workers Union official, who spoke with the driver, said the man was the only person on the bus. He put a piece of paper up to the driver's partition that said, “Don’t scream. Give me all your money,” the official said. 

The driver, a mother of two, gave the robber money that was meant for her babysitter, the union official said. The man made away with $100, cops said.

Before fleeing, the man hit the driver in the forehead with the handle of the knife, police said. He then ran away on East 119th Street toward Third Avenue, they said. Police did not have a description of the suspect.

The driver was taken to Harlem Hospital Center in stable condition. 

Transport Workers Union Local 100 President John Samuelsen called on the Metropolitan Transportation Authority and city to “better protect NYC Transit Workers.”

“While most of the city was asleep, our Bus Operator was out there performing this vital service only to be attacked by another dangerous criminal,” Samuelsen said in a statement. “This must stop.”