The incident occurred late on Saturday but was reported to the police on Sunday after the victim and her mother registered a complaint of rape and physical assault in Gazipur in east Delhi.
The victim told police that she had gone to meet her "Facebook friend", identified as Alok, at the Paper Market on Saturday night.
While they were walking on the road, a man, in his 40s, who was apparently under the influence of alcohol, abused them for coming out so late at night, a police officer told IANS.
"When the victim reached near Sapera Basti, the accused took advantage of the darkness and gagged and beat her," according to an FIR lodged in Gazipur Police Station.
"He threatened to kill her... and dragged her into a drain where he sexually assaulted her," the FIR said.
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