The victim, a resident of Jevur Patoda village in Kopargaon taluka of Maharashtra's Ahmednagar district, used to live with her sister.
Yesterday morning, when she went out of her house, the accused forcibly took her a little away from there and sexually assaulted her at an agricultural field and fled, police said.
The woman, who could not explain the incident verbally, gave a written complaint mentioning details of the offence.
Police have registered a case against the unidentified persons under relevant sections of IPC and launched a search to nab them.
The woman has been admitted to Ahmednagar Civil hospital for treatment, police added.