While the railways maintained that five people were killed in the accident, a senior Uttar Pradesh police official initially said seven died.
Additional Director General (Law and Order) Anand Kumar told media in the morning that seven people were killed and between 30 and 35 injured in the derailment.
However, Northern Railway Divisional Regional Manager Satish Kumar said five persons died.
"There was some confusion initially," the railway official said, adding that the condition of two of the patients was very serious.
There was similar confusion over the number of coaches derailed in the accident. The railways said five coaches went off the tracks after earlier putting their number at nine.
Ten women and six minors were among the injured, railway officials said.
She said there was confusion over a very seriously injured patient who was initially thought to have died.
Four of the seriously injured are being treated at the trauma centre of Lucknow's King George Medical University and two at the city's Sanjay Gandhi Postgraduate Institute of Medical Sciences, government spokesperson Shrikant Sharma told reporters.
The other injured were taken to Rae Bareli, about 80 km from the state capital Lucknow, officials said.
(With inputs from agencies.)