A middle-aged Dalit woman was allegedly gang-raped in Uttar Pradesh's Jewar area near Noida at gunpoint, police officials said on Monday, as opposition political parties, including the BSP and the Congress, demanded action against culprits.

None of the four accused have been arrested yet over the incident that took place on Sunday morning outside a village even as multiple police teams were formed and surveillance teams, along with dog squads, deployed to probe the case, the officials said.

Deputy Commissioner of Police (Women and Child Safety) Vrinda Shukla said, "The incident took place between 9.30 am and 10.30 am on Sunday in open fields near the village where the rape survivor often went to cut grass and the accused also went often to graze his cattle. Both are from the same village and known to each other well."

The key accused, who is a drug addict, had dragged the woman into the fields and forced himself on her, according to the police officer, even as local officials said the woman was raped at gunpoint.

"The role of other people in the act could be ascertained after investigation. The key accused is on the run and details could be confirmed after his arrest," she said.

DCP Shukla said the rape survivor was taken to the district hospital after the incident where her health condition was stable on Monday.

The police said an FIR has been lodged under relevant sections of the law on the basis of a complaint by the woman's husband and an investigation is underway.

BSP chief Mayawati condemned the incident, while a Congress delegation from Noida went to meet the family of the rape survivor.

"The gang-rape of a Dalit woman in Gautam Buddh Nagar is extremely sad and shameful. The BSP demands that the BJP government in UP take strong action against the accused persons, and give justice to the affected family," Mayawati said in a tweet in Hindi.

Congress leader Pankhuri Pathak, who led a party delegation to meet the Dalit woman's family, described the incident as a "heinous crime" and alleged failure of law and order in the region.

"Jewar's name is now heard often because of an airport being developed in the area but this incident of gang-rape gives one an idea of the law and order situation in the area, which is close to Delhi," Pathak said.

She added that the delegation was going to meet the family on instructions of the Congress high command.

Azad Samaj Party chief Chandra Shekhar Aazad also hit out at the Yogi Adityanath government over the incident.

"In Gautam Buddh Nagar, a Dalit woman was gang-raped at gunpoint by barbarians and casteist slurs were hurled at her. The barbarians have no fear of the law. Law and order has completely failed in UP. Dalit lives are in danger every moment and the incompetent government remains a mute spectator," he said in a tweet in Hindi.