Sniffer dogs have been brought in to help search for a three-year-old from Britain who may have been abducted on holiday with her family in Portugal.
Madeleine disappeared while her parents were at a nearby restaurant
Madeleine McCann's parents, from Leicestershire, were at a restaurant near the Mark Warner Ocean Summer Club in Praia da Luz when she went missing.
Kate and Gerry McCann returned at about 2145 GMT to find an empty bed and the apartment door and window wide open.
The apartment has been cordoned off and local people are helping with a search.
Gill Renwick, a friend of the family, said Madeleine's parents - both doctors - had been having a meal in a tapas restaurant a few hundred yards from the apartment and had been checking on the little girl and her younger brother and sister (two-year-old twins) every half hour.
"They're a devoted family and love their children to bits. They live for their children."
Madeleine was reported missing at about 2200 BST on Thursday and tourists joined the police in an all-night search.
The McCann family had been holidaying with a larger group
Her aunt Trish Cameron, who lives in Glasgow, said she felt certain her niece had been abducted.
"They last checked at half past nine and they were all sound asleep, sleeping, windows shut, shutters shut.
"Kate went back at 10 o'clock to check. The front door was lying open, the window had been tampered with, the shutters had been jemmied open or whatever you call it and Madeleine was missing...
"She's an absolutely beautiful, wee blonde girl, blue-green eyes - one distinguishing feature is that one of her pupils runs into the iris of her right eyes. She's an absolutely gorgeous wee girl."
She added: "We feel that what's been going on in Portugal has been ineffectual.
"My brother and sister-in-law are absolutely distraught."
But the manager of the Mark Warner resort in Portugal, John Hill, said about 60 staff and guests at the complex had searched until 0430 GMT while police notified border police, Spanish police and airports.
Officers sealed off the area of the apartment for forensic checks and extra police teams were brought in from Lisbon.
"As you can imagine Madeleine's parents are distraught and not doing very well at all," Mr Hill said.
"It's still questionable as to whether it's abduction," he said.
"We are hoping that Madeleine is found as soon as possible and safe and well."
The holiday firm has offered to fly other family members out to the resort.
A spokeswoman from the Portuguese police said they were being careful with the information being released.
"It is a sensitive case, it involves a child and we cannot give more information for now."
The British Embassy confirmed it had been informed about the toddler's disappearance.
The family was on holiday with a group of nine adults and eight children.
The toddler's father is a consultant cardiologist at Leicester's Glenfield Hospital.
Doug Skehan, another consultant cardiologist there, said: "(Dr McGann) is a popular hard working colleague, for whom we have great affection.
"The mood in the hospital is one of great concern and we hope that Kate and Gerry will have their daughter back very soon."