A 7-year-old girl is in critical condition at a New Delhi hospital after undergoing surgery for injuries she suffered while being raped with a metal water pipe, officials said Wednesday.

Her mother was by her bedside after the girl underwent hours of surgery. The exact type of pipe used in the assault is unclear.

A 21-year-old has been arrested in connection with the rape, which occurred in the district of Shahdara in the northeastern part of the city, said Meghna Yadav, a deputy commissioner with the Delhi Police.

Yadav could not provide further details, she said. But Swati Maliwal, chairwoman of the Delhi Commission for Women, said the girl was in extreme pain after the attack.

"We are working out her rehabilitation plan," she told CNN. "It is very unfortunate that these rape cases are not ending in Delhi. Police resources continue to be extremely low in Delhi."

In a series of tweets, Maliwal provided additional details of the attack, saying the girl, who comes from a poor family, had been lured to a park in Seemapuri, where the perpetrator assaulted her. She was bleeding "incessantly" after the attack, Maliwal tweeted.

"Cannot describe the pain the little girl was experiencing. Already malnourished, she has a long struggle ahead," she added. "We are going to support her in her legal fight to ensure death penalty to her culprits. Will file compensation application & shall make all efforts to rehabilitate her." (CNN)