The incident occurred last evening when the woman, accompanying with her brother on a bike, was returning to her parental home in a village under Mandawar police station.
Four men on two motorbikes intercepted them a kilometre before the Preetam Singh gate here.
They assaulted and robbed the duo and took the woman to a field at gunpoint where one of them allegedly raped her, police said.
The duo have been admitted to the district hospital where their condition is stated to be stable.