The woman was five months' pregnant at the time of offence, police said quoting her medical examination report.
While the victim was alone at home in Ghoteghar village of Thane on Monday afternoon when her husband and other family members had gone to attend a marriage, two unidentified persons entered her house on the pretext of repairing a faulty cable, Shahapur assistant police inspector Bapusaheb Shinde said.
The duo tied her legs before they took turns to rape her. They also inflicted injuries on her body, including her private parts, he said.
Later, when her husband and other family members returned home at night, the woman informed them about the offence.
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The victim yesterday filed a complaint about the crime with Shahapur police.
The duo was booked under relevant sections of the Indian Penal Code (IPC) and a search was on to nab them, police said.
The victim was being treated at a government hospital in Shahapur, they added.