The accident occurred at around 5 AM when the bus, on its way to Haldwani town of Uttarakhand from here, rammed into the mini-truck, carrying people from Garhmukteshwar, they said.
Seventeen people died on the spot while four of the victims succumbed to their injuries at the hospital, Bulanshahr SSP Gulab Singh said.
The twentyeight injured have been admitted to government hospitals, he said.
Police and Health department personnel have reached the spot and rescue operations are underway, the SSP said.