Police and mountain rescue teams worked through the night to try to find five-year-old April Jones, who has been missing since Monday evening.
April was last seen getting into a light-coloured van at around 7pm on Monday. She had been playing with a friend on the estate where she lived, in Machynlleth, Powys.
Overnight a team of 40 officers, dog handlers and mountain rescue teams searched riverbanks near April's home, concentrating their efforts on the River Dyfi.
Yesterday Dyfed Powys Police arrested a 46-year-old man arrested in connection with April's disappearance. The man, who remains in police custody at Aberystwyth Police Station, has been named locally as Mark Bridger, but police have refused to identify him.
Police say they have recovered a Land Rover vehicle and it is being looked at by forensic officers.
Hundreds of local people helped to look for April yesterday, but last night officers scaled back the public search, saying the presence of vast crowds could "compromise" the search.
Specialist teams worked through the night using thermal imaging equipment.
In a press conference at just after 7.30am today, police said volunteers were no longer needed. "Can we please leave this now to the trained and skilled people that we have," said Supt Ian John.
He later added: "I don't want those officers to be distracted by the well-intentioned and enthusiastic support" of the public.
Supt Ian John also reminded the public of the "challenging conditions" in the area, which is rural. The poor weather overnight has resulted in the flooding of the River Dyfi, he added.
Supt Jones also explained that based on experience police expect to find April Jones close to where she went missing.
In a statement read out at a press conference last night, April's family said they were "shattered" by her disappearance.
They described her as a "beautiful little girl" and said: "Please, please if you have our little girl, let her come home to us."
Thousands of people have turned to social networking sites Twitter and Facebook to express their concern for April and her family.
Once Facebook Page, Find April Jones, has 127,704 'likes'.
Meanwhile April topped Twitter's trending list yesterday, with thousands of users discussing the unfolding situation.
UPDATE 1035: Police have confirmed the 46-year-old man arrested is indeed Mark Leonard Bridger, and they have released an image of him.
They have also released an image of a Land Rover Discovery recovered from a repair garage on Tuesday afternoon. The vehicle's registration is L503 MEP.
Police are appealing to the public to think back to whether they saw Mark Bridger or the vehicle between 5pm on Monday and 3.30pm on Tuesday. "If you did, please don't assume that someone else has already contacted us," police told a press conference at just after 10.30am.
Even the smallest piece of information could be "crucial", police stress.
Police also said Bridger was wearing a camouflage green jacket and black waterproof trousers with camouflage trousers underneath when he was arrested on Tuesday afternoon on the A487.
UPDATE 1235: April's mother Coral Jones has made a desperate plea for information about her daughter's whereabouts.
Speaking at a news conference, Ms Jones was in tears as she said: "It's been 36 hours since April was taken from us. There must be someone out there who knows where she is and can help the police find her.
"We are desperate for any news. April is only five years old. Please, please help us find her".
Det Superintendent Reg Bevan reiterated the police's appeal for information: "In relation to this specific investigation we are pursuing a number of lines of enquiry, and Mark Bridger is one of them," he said.
"Please look at these images – did you see this vehicle between Monday evening and Tuesday afternoon?
"Do you know Mark Bridger, and did you see him again between Monday evening and Tuesday afternoon?"
He added that more than 50 volunteers had assisted mountain rescue teams in their search for April, and that police have details of many more volunteers who are able to assist. "Their support has been vital," he said.
UPDATE 1440: Divers are searching the River Dyfi, BBC News reports.
Meanwhile details about Mark Bridger are emerging in the national press.
According to the Guardian he was born in Sutton, south London, and has lived in Machynlleth for more than 25 years.
The Ministry of Defence is checking reports that Bridger is a former soldier, the newspaper reports.
Locals said Bridger worked as a lifeguard at Machynlleth leisure centre, where volunteers gathered on Monday night to hunt for April.
He is the father of at least three children, says the Guardian; one with his ex-wife – a boy who is now 20 – and another boy and a girl, now aged 12 and 10, with a girlfriend with whom Bridger lived in Machynlleth from the late 1990s after his marriage collapsed.
UPDATE 1500: Police are searching outbuildings near the house of Bridger, BBC News reports.
UPDATE 1513: Four or five canoeists and kayakers are moving down the fast-moving River Dyfi, BBC News reports.
The stretch of river being examined is around half a mile outside Machynlleth, BBC News explains, and the A487, where Bridger was yesterday arrested, runs parallel to the river.
Around 20 river bank searchers passed the BBC reporter on foot, each roped to one another.
Banks of the river are being combed by "an army of police officers", the BBC reports.
UPDATE 1540: Police are sealing off a section of the River Dyfi near where Bridger was arrested, and a nearby BBC reporter has been asked to vacate the area.
Anyone with information is urged to call 101. Alternatively, Dyfed Powys Police have issued a number for people who might have details about April: 0300 2000 333.