"The family was on a motorcycle, passing through Sondiha when the three were stopped by armed men. They raped the mother and the daughter after tying the father to a tree," said senior police officer Nayyer Hasnain Khan.
The man, who runs a clinic in Gaya's Guraru Bazar, shut shop around 8 pm on Wednesday night and was heading home with his wife and daughter.
When they were passing through a deserted stretch, the group of 20 surrounded them. In his statement to the police, the man said he tried to fight the men but was overpowered.
The officer in charge of the police station that oversees the area has been suspended for negligence. Eleven suspects were picked up on Wednesday and the rest yesterday. Local villagers reportedly helped the police catch the accused by putting up roadblocks to block their escape.
"It also emerged during the investigation before this incident, the same group had snatched mobile phones and cash from a couple of students passing through the village," Mr Khan said.
Amid outrage and shock over the incident, RJD leader and former deputy chief minister Tejashwi Yadav targeted Chief Minister Nitish Kumar over the state of law and order. "Nitish Kumar, after joining hands with the BJP, has buried law and order in the state," he told NDTV.