Rescue efforts are continuing into the night to try to free scores of workers trapped when a building being built in the Kenyan capital, Nairobi, collapsed.
At least seven people were killed when the four-storey building fell.
About 200 people were thought to be in or around the building. Several are trapped in the basement and are short of oxygen, rescuers said.
More than 100 people are in hospital, some with critical injuries. Urgent appeals for blood have been made.
The BBC's Karen Allen at the scene of the collapse says that although there is now lifting equipment at the scene, in places rescuers are still having to pick away huge slabs brick by brick.
Kenyan authorities say international teams will be on site soon with thermal imaging equipment.
President Mwai Kibaki is to cut short his visit to Sudan to coordinate rescue efforts, a statement said.
Farid Abdulkadir, head of disaster operations with the Kenya Red Cross Society, said four people had died at the site, while a hospital spokesman said three more had died in hospital.
Calvince Omondi, a volunteer rescuer, told AFP news agency that contact had been established with several people trapped in the building's basement.
On TV footage, a hand could be seen waving for help from under a concrete beam at the site on the corner of Ronald Ngala St and Tom Mboya St, in the River Road area.
Several people were pulled from the building to cheers from the onlookers.
Thousands of people flocked to the scene in central Nairobi, blocking access for the army and rescue workers.
After a while, riot police arrived and used truncheons to beat back the crowds, the AP news agency reports.
Both Police Inspector Matthew Limo and Kenyan Housing Minister Soita Shitanda suggested that building regulations had been flouted, 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.
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 the 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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