The raid was jointly conducted by Delhi Police and a team from Bachpan Bachao Andolan (BBA), following a tip-off.
On interrogation, the placement agency's owners purportedly confessed that they were involved in child trafficking and paid Rs 15,000 per child, police said.
A search is also on to find the whereabouts of another 13-year-old girl, hailing from Jharkhand, who came to Delhi in 2009 after being promised a secure job and has been missing since, they said.
"We are interrogating the placement agency's owners for clues leading to the girl's whereabouts," a police official said.
