Police found the couple, who are Spanish citizens, around 11 p.m. local time (1730 GMT) on Friday on a roadside, looking like they had suffered a beating, Pitamber Singh Kherwar, superintendent of police in Dumka in eastern India, told reporters on Saturday.
He did not give details on the crime or identify the victims, adding the two people told authorities "their modesty had been outraged", in an incident involving seven men.
The couple, who identified themselves as Vicente and Fernanda to Spanish TV channel Antena 3, said in a video interview on Saturday that the men raped Fernanda and hit Vicente repeatedly.
The couple said they had camped out near the site where they were attacked because they could not find hotels nearby.
"They raped me, they took turns while some watched and they stayed like that for about two hours", Fernanda, who has joint Brazilian-Spanish nationality, said in the interview.
Earlier this weekend, the couple published a video describing what happened on their joint Instagram account, where they post images of their travels around the world by motorcycle to almost 200,000 followers. The video is no longer available.
In a new video, Vicente and Fernanda, who appears with bruises on her face, thanked their followers for the support.
The Spanish Foreign Ministry said on Sunday it was sending staff to the area and had been in touch with authorities, while its Brazilian counterpart said it had sought contact with the Brazilian citizen through its embassy in New Delhi and was available to give every assist applicable.
Kherwar, the superintendent of police in Dumka, said on Saturday one of the people detained had given the authorities names of other people involved. Kherwar added that a forensic science laboratory was helping in the case.
