The vehicle of the patrol team hit a tree and overturned late last night in an area under the Kotwali Lalganj Police Station, they said.
The incident occurred after the driver lost focus. Four of the five injured policemen are admitted at the Lalganj Community Health Centre, police said.
Sub-Inspector Gaya Prasad, whose condition was stated as serious, was referred by doctors to a hospital in Allahabad for treatment, police added.