NEW DELHI -- An Indian juvenile court on Saturday handed down the first conviction in the fatal gang rape of a young woman on a moving New Delhi bus, convicting a teenager of rape and murder and sentencing him to three years in a reform home, lawyers said.

The victim's parents denounced the sentence, which was the maximum the defendant faced. The family had long insisted the teen, who was 17 at the time of the December attack and is now 18, be tried as an adult -- and thus face the death penalty -- insisting he was the most brutal of the woman's attackers.

"He should be hanged irrespective of whether he is a juvenile or not. He should be punished for what he did to my daughter,'' the victim's mother, Asha Devi, told reporters after the verdict was announced.

Indian law forbids the publication of the teen's name because he was sentenced in a juvenile court.

The attack, which left the 23-year-old victim with such extensive internal injuries that she died two weeks later, sparked protests across the country and led to reforms of India's antiquated sexual violence laws. The government, facing immense public pressure, had promised swift justice in the case.

The convicted teen was one of six people accused of tricking the woman and her male companion into boarding an off-duty bus Dec. 16 after they had seen an afternoon showing of "Life of Pi'' at an upscale shopping mall. Police say the men raped the woman and used a metal bar to inflict massive internal injuries to her. They also beat her companion. The victims were dumped naked on the roadside, and the woman later died from her injuries in a Singapore hospital.

The victim's father said the family was deeply disappointed with the sentence.

"This is completely unacceptable to us,'' Badrinath Singh said. "We are not satisfied with this outcome. He is virtually being set free. This is very wrong.''

"No family should have a daughter if this is the fate that lies ahead for women. In this country, it is crime to be born a girl,'' he said.

Indian law forbids the publication of the names of rape victims, even if they die.

S.K. Singh, a lawyer for the victim's family, said they would challenge the juvenile court's verdict in a higher court.

"We will also seek a review of the man's age by a medical panel, since we believe he was not a juvenile when the incident took place,'' he said.

In India, especially in rural areas, many people do not have their births properly registered, and school certificates are used as proof of age.

Singh and the defendant's lawyer, Rajesh Tewari, both confirmed the conviction and sentence.

Reporters were not allowed inside the courtroom. Scores of television crews lined up on the road outside the court building beginning early Saturday, waiting for the verdict.

Four of the other defendants are being tried in a special fast-track court in New Delhi and face the death penalty. The sixth accused was found dead in his jail cell in March. The court is expected to hand down the rest of the verdicts in September.

The convicted defendant was tried as a minor on charges including murder and rape. The time he has spent in a juvenile home since he was arrested in December will count toward his sentence, Tewari said.

The attack set off furious protests across India about the treatment of women in the country and led to an overhaul of sexual assault laws.

A government panel set to suggest reforms to sexual assault laws rejected calls to lower the age at which people can be tried as adults from 18 to 16.

In July, India's top court also refused to reduce the age of a juvenile from 18 to 16 years. However, it later agreed to hear a new petition seeking to take the "mental and intellectual maturity'' of the defendant into account, and not just age.

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  • Indian schoolchildren hold candles and placards during a prayer ceremony in Ahmadabad, India, Monday, Dec. 31, 2012. (AP Photo/Ajit Solanki)

  • Indian policewomen stand guard during a protest in New Delhi, India, Monday, Dec. 31, 2012. (AP Photo/Manish Swarup)

  • An Indian student shouts slogans during a protest rally in Hyderabad, India, Monday, Dec. 31, 2012. (AP Photo/Mahesh Kumar A.)

  • Indian people shout slogans during a protest in New Delhi, India, Monday, Dec. 31, 2012. (AP Photo/Manish Swarup)

  • Indian Rapid Action Force personnel in riot gear keep watch during a demonstration following the death of a gang rape victim in New Delhi on December 31, 2012. (RAVEENDRAN/AFP/Getty Images)

  • Indian demonstrators gather following the death of a gang rape victim in New Delhi on December 31, 2012. (RAVEENDRAN/AFP/Getty Images)

  • Indian demonstrators perform a prayer ritual in memory of a gang rape victim in New Delhi on December 31, 2012. (RAVEENDRAN/AFP/Getty Images)

  • A member of the student wing of India’s main opposition Bharatiya Janata Party vandalizes a police barricade during a protest after the death of a young woman who was recently gang-raped in a moving bus in New Delhi, India, Sunday, Dec. 30, 2012. (AP Photo/Altaf Qadri)

  • An Indian lights a candle as she mourns the death of a young woman who was recently gang-raped in a moving bus in New Delhi, India, Sunday, Dec. 30, 2012. (AP Photo/Altaf Qadri)

  • Members of the student wing of India’s main opposition Bharatiya Janata Party try to break through a police cordon during a protest after the death of a young woman who was recently gang-raped in a moving bus in New Delhi, India, Sunday, Dec. 30, 2012. (AP Photo/Altaf Qadri)

  • Indian protesters hold candles and posters during a rally in Ahmedabad on December 30, 2012, following following the cremation of a gangrape victim in the Indian capital. (SAM PANTHAKY/AFP/Getty Images)

  • Indian protesters burn an effigy depicting rapists during a rally in New Delhi on December 30, 2012, following the cremation of a gangrape victim in the Indian capital. (Andrew Caballero-Reynolds/AFP/Getty Images)

  • Indian protestors scuffle with police officials during a rally in New Delhi on December 30, 2012, following the cremation of a gangrape victim in the Indian capital. (RAVEENDRAN/AFP/Getty Images)

  • A young Indian child holds a lighted candle as she joins others during a protest rally in Ahmedabad on December 30, 2012, following the cremation of a gangrape victim in the Indian capital. (SAM PANTHAKY/AFP/Getty Images)

  • Members of Bharatiya Janata Party (BJP) Mahila Morcha take part in a candlelight march in Amritsar on December 30, 2012. after the cremation ceremony for a gangrape victim. (NARINDER NANU/AFP/Getty Images)

  • Indian protestors shout slogans during a rally in New Delhi on December 30, 2012, following the cremation of a gangrape victim in the Indian capital.(RAVEENDRAN/AFP/Getty Images)

  • Indian residents shout anti-government slogans as they take part in a protest in New Delhi on December 30, 2012, after the cremation ceremony for a gangrape victim. (RAVEENDRAN/AFP/Getty Images)

  • An Indian protester holds placards during a rally in New Delhi on December 31,2012. The family of an Indian gang-rape victim said they would not rest until her killers are hanged as they spoke of their own pain and trauma over a crime that has united the country in grief.(SAJJAD HUSSAIN/AFP/Getty Images)