At least three people have been rescued from the debris of an unfinished five-storey building the day after it collapsed in Kenya's capital, Nairobi.
Rescue efforts have been boosted by assistance from an Israeli team with sniffer dogs and heavy rescue equipment, US troops and a UK team.
At least 12 people are known to be dead with more casualties expected. Some 100 people have been taken to hospital.
Kenya's president has visited and said they should learn from the Israelis.
Rescuers are concentrating on four areas where they have heard noises.
They have been drilling air holes and using specialist cutting equipment and detection devices.
Major General Yitzhak Girshon, the commander of the Israeli team that arrived early on Tuesday, told reporters they would be working hard to save as many people still alive as they could.
"If there are holes or air pockets, we can save many people," he said.
In the afternoon, an unidentified man was brought out of the ruins on a stretcher to cheers from onlookers. Two survivors were pulled out by Kenyan rescuers just before dawn.
About 200 people were thought to be in or around the building when it collapsed on Monday. The building was still under construction at the time.
The BBC's Karen Allen, at the scene, says that although more heavy lifting gear has been brought in, much of the debris is having to be moved by hand because of fears that other parts of the building may collapse.
A criminal investigation has been opened into the accident.
President Mwai Kibaki cut short a visit to Sudan to visit the site and promised they would learn from the well-equipped Israeli team to ensure they were prepared in future.
"It is too soon for us to say anything of what has happened, but we have to have courage and we have to work hard," he said.
Both Police Inspector Matthew Limo and Kenyan Housing Minister Soita Shitanda suggested that building regulations had been flouted, news agency AFP reports.
"If there was any planning approved by the city council, that plan was not followed to the letter or it was not a proper plan," Mr Shitanda said.
A letter warning that the building was unsafe had been sent to a Kenyan newspaper in December.
One worker, James Ofunyi, said the workers were on their lunch break, with many asleep in the building when it collapsed.
"I was taking a nap after having had lunch when I heard someone shouting to run, but I didn't get downstairs fast enough because the building started falling," he told AP news agency.
"I jumped to the other side."
According to a Reuters news agency reporter, some of the concrete was still wet.
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