The incident took place when Naresh and Meena, residents of Indirapuram in Ghaziabad, were going to Nangloi on the motorcycle, a senior police official said.
Both of them received head injuries and were taken to the Sanjay Gandhi Memorial Hospital where Meena was declared brought dead.
"The condition of Naresh, who is undergoing treatment, is said to be critical," the official said, adding the driver of the bus managed to escape.
Police seized the low-floor non-AC bus.
