More than 80 officers, including some redirected from Olympics duties, are involved in the hunt for missing 12-year-old Tia Sharp, police have said.
Metropolitan Police area commander Neil Basu, whose son once went missing for two hours in what he described as the "worst two hours" of his life, said: "I can't imagine how it must feel for this family after five days."
Tia, who has never gone missing before, seemingly vanished without a trace on Friday afternoon after telling relatives she was going to the Whitgift Centre in Croydon.
She is thought to have been last seen at the house where her grandmother Christine Sharp, 46, lives with her partner Stuart Hazell, 37, at the Lindens, New Addington, south east London.
It was thought the last person to see the 12-year-old was her grandmother's partner Stuart Hazell, to whom she shouted she would be "back by six". He was seen being led from Mrs Sharp's house by two men in plain clothes, and was put into a car and driven away. Police said a man in his 30s was being interviewed as a witness but has not been arrested. Mr Hazell later returned home after helping police with their inquiries.
Mr Basu revealed Scotland Yard has received more than 300 calls and 60 reported sightings of Tia, including a member of the public who came forward, saying they saw Tia leaving her grandmother's house at about noon on Friday, the day she disappeared.
But Mr Basu said police could not be "absolutely sure" who the last person to see Tia on the estate was. He stressed the investigation remains a missing persons inquiry, with no suspects, adding: "I am looking to find Tia safe and well."
He said his own son had gone missing at a similar age, adding: "It was, still is, the worst two hours of my life. The family want Tia home, they miss her dreadfully."
He said Olympics resources have been redirected to the search which now involves more than 80 officers - 40 detectives and 40 specialist search officers.
"We have collected more than 800 hours so far of CCTV footage from buses, trams, and we have viewed more than 120 hours of that," he said, adding that it was a 24/7 process and police will continue to collect more CCTV. Searches have covered a 500m radius around Tia's grandmother's house, including woodland, garages, lock-ups and a local school.