The stepfather of missing 12-year-old schoolgirl Tia Sharp has said the family is "in bits" and urged people to find "my little girl".
David Niles, 29, said Tia's mother Natalie was distraught and he had not slept for four days.
Tia disappeared after leaving her grandmother's home in Croydon, south-east London, at about midday on Friday.
CCTV stills of Tia taken outside the nearby Co-op the day before have been issued by police.
On Tuesday evening, around 100 local people gathered at Croydon Rugby Club to search for Tia.
Club secretary Sue Randall said: "We were here last night with the police and they told us all to come back today.
"At the moment there's about 100 people but more came and went off to start the search."
She said people would search for "however long it takes".
Earlier, police began searching a local wood, Birchwood, which is less than a mile from Tia's grandmother Christine Sharp's home in New Addington.
A team of nine officers dressed in blue police baseball hats used long sticks to scour the undergrowth.
Police said there had been 55 reported sightings of the girl, but these were yet to be confirmed.
Wearing a T-shirt bearing Tia's image, Mr Niles said: "I just want to find my little girl.
"We're in bits, the whole country has helped us and is supporting us.
"I haven't slept in four days. Natalie (Tia's mother) is in bits."
'Good as gold'
He said he last saw Tia on Thursday morning at the family home in Mitcham before he headed to work.
"She was good as gold," Mr Niles said.
"I know I am not her real dad, but I have been there since day dot.
"When she left the house she shouted 'Bye' and 'See you by six'."
Tia's grandmother said she was pinning her hopes on new CCTV stills of Tia taken outside the Co-op in Featherbed Lane near her house at about 16:15 BST on the day before she went missing.
The girl was wearing similar clothes when she was last seen leaving her grandmother's house on Friday.
Speaking from her terrace house where a solitary candle burns outside in a glass holder, Mrs Sharp said: "We're hoping the pictures will jog someone's memory."
She thanked the community for supporting the family.
A campaign has also been launched on the social networking site Facebook, while The Sun newspaper has offered a £25,000 reward for information that will help police find Tia.
Police have scoured hours of CCTV footage but have not found any trace of Tia, who has never gone missing before.
She had been on her way to the Whitgift shopping centre, in Croydon, when she went missing.
On Monday, Tia's uncle David Sharp, 28, urged anyone who knew where his niece was to come forward.
Det Ch Insp Nick Scola, from the Met's Homicide and Serious Crime Command, said the youngster spent a lot of time at her grandmother's house and the last person to see Tia was her grandmother's partner, but on Tuesday Tia's stepfather said he was not sure about that.
Mr Scola said: "She [Tia] told her grandmother's partner she was going out.
"He was the last person to see her, that we are aware of at this time.
"We have recovered a number of items but we now know that they do not belong to Tia."
Police said Tia went there the previous day after travelling by tram, with her grandmother's partner meeting her half-way at East Croydon station.
Officers are particularly keen to hear from anyone in the Lindens area of New Addington who has information and appealed for any bus or tram drivers in the Croydon area who recognise Tia's description to contact them.
She is known to frequent the Croydon, Mitcham and Wimbledon areas.
Tia is described as white, 4ft 5in tall and slim, and was wearing FCUK glasses.