A senior police officer said the incident occurred last night after the girl was abducted while she was playing outside her home at jhuggis near 'Brittania railway lines'.
He said the girl's parents informed the police around 8 PM, but she could not be found despite a four-hour search.
A missing persons complaint was filed thereafter and efforts were again made to search the girl with her parents and neighbours, he said.
Her body was found this morning near the railway tracks with injuries which indicated she was sexually assaulted before being strangulated, the officer said.
"In the CCTV footage that we have found from a factory, we have seen two men taking away the girl. They live in the same area as the girl's family but they have been absconding. Efforts are being made to nab the accused," said the officer.
The girl's parents told police the two men who were seen in the CCTV footage were also searching for the girl yesterday.
The girl's family had been living in the area for the last 20 years. Her father works as a porter at a godown. The family has six daughters, including the victim.
"Met family of the girl. A 4-year-old girl was raped last year in exact same place. Nothing has changed since. The area is very unsafe(sic)," she tweeted.
Maliwal also expressed concern about Delhi being unsafe for women.
"4-year-old girl raped and murdered by 25-year-old man in Keshavpuram. How low will humanity stoop? Delhi is so unsafe for women and girls.
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