The victim, 23, along with his brother had been residing in a rented house at Shibrampur of the town for the last two months, said officer-in-charge of Sadar Police Station Obaidul Haque.
Her brother, a garment worker, did not return home on Wednesday night due to pressure of work, he said.
Taking the advantage, four youths of the area entered the house around 2am on Thursday with the help of the house owner and raped her one after another.
However, she disclosed the matter when his brother returned home on Thursday night.
As the victim fell sick on the night, she was taken to Pabna Medical College Hospital in the early hours of Friday.
Dr Nargis Sultana of the hospital said they found the evidence of gang-rape in primary test.
Meanwhile, police arrested landlord Haidar Ali, said Superintendent of Police Sheikh Rafiqul Islam. “’We’re carrying out drives to arrest the rapists,’’ added the SP.