Shocking details have emerged of the torture, gang rape and murder of a low-caste woman in northern India.

A post-mortem of the 23-year-old revealed that sharp objects were inserted into her vagina. The attackers smashed her skull with bricks and ran over her with a car, in an attempt to conceal her identity. The body was left in a field for stray dogs to feed on.

The victim's body was found by passersby on 11 May, two days after she went missing. The body was so badly mutilated that it could only be identified by her family by the clothes she wore at the time of her disappearance.

Findings from the post-mortem said that the victim's "oesophagus [food pipe] was missing and gnawing effects were seen over [the] chest. Her face, tongue, eyes and ears were totally distorted. Her face was not identifiable."

Police have arrested two men – Sumit, 24, and Vikas, 28, (only their first names were released) – in connection with the brutal sexual assault, while six others are also being questioned.

Family members of the victim, whose name has not been revealed, accuse six others of being involved in the gang-rape.

"When she said to them she would complain they hammered her skull in with bricks. The way that they brutalised her is horrific," said senior police official Ashwin Shenvi, adding that the medical examination suggests she was drugged before the violent sexual attack.

The victim's mother claims she filed a complaint with the local police against Sumit, the main suspect who wanted to marry the victim, three months before the attack, but it was ignored. Officials have promised to look into this claim.

Haryana police have formed a special investigation unit for the case, while the government has promised severe punishment for the perpetrators. "Culprits involved in such ghastly acts won't be spared. Will ensure speedy justice by fast track courts," Haryana Chief Minister Manohar Lal Khattar said.

The incident has sent shockwaves across Haryana – the northern state which surrounds the Indian capital territory of Delhi on three sides.

The attack is a grim reminder of the Delhi gang-rape, in which a 23-year-old physiotherapy intern suffered a similar attack and later lost her life. The Supreme Court recently upheld the death penalty for the four convicts involved in the incident.