An Unjha police official said the woman and the man were talking to each other sitting in a vehicle when the two men arrived on their two-wheeler and threatened the woman's colleague with a knife.
The duo then allegedly stripped the man and beat him, the police said, adding one of the two assaulters then tied the woman's hands and legs with her sari before both of them took turns to allegedly rape her.
The incident took place between 9 pm and 11 pm on Tuesday night, the police said.
"In the morning, people heard the cries of the woman and they informed us. We took her to the police station and she stated in her complaint that the rapists were aged between 25 years to 30 years," the police said.
The woman's male colleague was brought in an unconscious condition to the police station and both of them were later admitted to the Mehsana Civil Hospital, the police said.
Mehsana local crime branch police inspector H P Dave is investigating the case, an Unjha police official said.