The authorities formed a special team to find the perpetrators, police said on Sunday.

According to the victims, the gang stopped the family car on a busy highway in Uttar Pradesh state, some 65 kilometers (40 miles) south of New Delhi, in the night between Friday and Saturday. The mother counted six attackers.

"The men allegedly dragged the family to a nearby field and looted cash, jewelry and mobile phones," said local police officer Rameshwar Singh. "They later allegedly tied the men of the family with ropes and raped the mother and her 13-year old daughter."

Country struggling against sex violence

Police has detained 16 people on Sunday. However, the officials were still searching for the leader of the attackers.

"The main suspect has been identified. We are trying to arrest him as soon as possible and send him to jail under stringent sections of the law," said police representative Daljeet Chaudhary to the AFP news agency.

India has been trying to rein in sexual violence after a brutal attack on a New Delhi bus sparked public outrage in 2012. Despite tougher anti-rape laws, sexual assaults remain relatively common.

Earlier this year, a 15-year old girl was raped and set on fire near the Indian capital, and a 14-year old died last week after the same group of people raped her for the second time.

dj/rc (dpa, AFP)