Five members of a family, including two children, were killed when an unidentified vehicle hit their motorcycle on the Shahjahanpur-Lucknow road in the Shera Mau Dakshin area here on Friday.
Circle officer Amit Chaurasia said the incident occurred in the early hours of Friday when the victims were returning home after attending a wedding function.
The deceased have been identified as Raghuveer, 34; his wife Jyoti, 30; sister-in-law Julie, 36; and children Abhi, 3, and Krishna, 5.
Head injuries are said to be the likely cause of deaths.
The bodies have been sent for post-mortem and a probe into the matter was underway, the police official added.