Rescue workers have made contact with 11 people under the rubble of a building in South Africa.
At least six people died when the five-storey apartment block collapsed yesterday afternoon while under construction in George, a city 400km east of Cape Town.
Twenty-eight people have been taken from the debris, officials said, six of whom have died.
Forty-seven people are unaccounted for, including the 11 with whom contact had been established.
"We are in contact with 11 people" trapped under rubble, head of rescue operations Colin Deiner said.
Life has been detected under three areas of the site.
"They've been down there for more than 24 hours now, that's a long time" Premier of the Western Cape province Alan Winde said.
Recalling that the international standard for rescue operation is three days, he said the second day would be "critical".
Authorities also added that they had advised the 11 to switch their phones on and off to preserve battery power.
The main focus is to get everyone out, Mr Deiner said.
"Once we have got all the people that we know about out, we are going to start a process called delayering.
"We would then start lifting the different floors off each other," he said, adding it would be "tricky" to remove the concrete trapping the building workers.
A construction crew of 75 people was on site at the time of the collapse at around 2pm local time (1pm Irish time) yesterday, authorities said.
Three rescue teams are working on three different areas of the collapsed building, which include an underground car park.
The reasons for the collapse are not known.
The construction plans for a 42-unit apartment block had been approved by the city in July.
South Africa's President Cyril Ramaphosa offered his "deep condolences to the relatives and friends" and said his thoughts were with the families of the dead and missing.
He called for an investigation, saying it must "bring closure to the community and prevent a repeat of this disaster".
George, which has a population of about 160,000, is a picturesque coastal city located on the tourist trail along South Africa's southern coastline.
Photos shared by the city council showed a flattened construction site with emergency services on the ground.
The broken roof of the building is still clearly visible atop the pile of rubble.
Rescue operations continued throughout the night with floodlights illuminating the cordoned-off site.
A coordination post was set up to run the operations, which involve numerous emergency services and over 200 personnel.
More diggers and sniffer dogs were dispatched from Cape Town, emergency services said.
Officials said relatives of those trapped had been asked to gather at the city hall near the construction site, where they would be taken care of.
Religious leader and social workers were present to assist and comfort families, authorities added.
"Our thoughts are with the families and all those affected, who continue to wait for word of their loved ones," Mayor Leon van Wyk said.
But officials urged onlookers and members of the public to stay away from the "dangerous" site.
They also appealed to South Africans to refrain from posting fake news about the disaster.
George is run by the Democratic Alliance, the leading opposition party, which also controls the Western Cape province.
"No stone will be left unturned in making sure that we get to what caused this accident," Mr Winde vowed.
