Twelve people were killed and 63 injured when a bus in which they were travelling fell into a ditch near Uchasiya village in Fatehganj area in Bareilly district.
The bus was heading to Delhi from Bahraich when the accident happened on National Highway 24, police said.
The injured were admitted to a hospital where the condition of 10 of them was stated to be critical.
In another accident, nine people were killed and five critically injured, all of one family, when a car carrying them was hit by a speeding vehicle in Pilkhua area in Hapur district.
The dead included four women and three children, aged between two and eight, police said.
The family of one Harbeer was returning home after taking holy bath in river Ganga on the occasion of Amavasya when the accident happened at 4am, police said
"It appears a speeding truck or some other heavy vehicle has hit the car," a police officer said.
All the nine members of Harbeer's family died at the scene, they said.