The woman and her lover were labourers at a sago factory and were returning home last night when the four persons, who were also working at the factory, accosted them, they said.
They first assaulted the woman and her paramour and then raped her in front of him, and threatened them not to reveal the matter to anyone, police quoted the victims.
The woman told local people about the incident and they brought it to the notice of police.
Police said, the woman was married and had separated from her husband two years ago. Her two daughters were staying with her mother at Karur, 60 km from here.