A mentally unstable woman in her thirties, was gang-raped by a group of eight autorickshaw drivers in the Alambagh area of the state capital, police said on Tuesday.
Four of the nine persons accused in the gang-rape have been arrested by the Lucknow Police.
Five others, including a woman, are absconding.
According to reports, the woman, daughter of a retired railway employee, had gone missing on September 23 and her father lodged a missing complaint.
On September 24, he got a call from Alambagh police station and there he found his daughter injured and in torn clothes.
He then lodged a complaint of rape on the basis of which the police registered an FIR.
The woman told her father that a group of men had asked her to get into an autorickshaw, promising to drop her home.
Instead, she was taken to the railway colony in Alambagh where eight persons raped her and thrashed her. A woman was also there.
The men were traced by scanning CCTV footage of the area and arrested on Monday.
Additional Deputy Commissioner of Police (ADCP), Central Zone, Rajesh Srivastava, said an investigation is on in the matter and efforts are being made to arrest the remaining accused.