The seriously injured victims were taken to Kenyatta General Hospital, where six were in critical condition, said Dr. Samuel Ngiru, who works in the trauma department. "If we do not get more blood, people will die," he said.
"Some were lying down for a nap. They were too tired after working for at least six hours," food vendor Jane Wanjiru, 32, said. "We felt the building shake and those of us who were on the roof top jumped onto the roof of the next building. We then watched it collapse."
Immediately after the collapse, hundreds of people formed lines to carry away chunks of concrete and wooden scaffolding, which a front-loader then pushed away from the site. Dozens of soldiers, firefighters, police officers and Kenya Red Cross workers worked to free those trapped.
Construction workers said more than 280 construction workers were inside the building in central Nairobi. By nightfall, it was unclear how many were still trapped in air pockets and parts of the basement, officials said.
Dr. Gilbert Oburu, who was coordinating emergency treatment for survivors, said he saw five dead bodies at the site. Four additional people died while undergoing treatment, a hospital spokesman said.
Oburu said rescue workers brought out at least 68 survivors. They dug frantically into the rubble with bare hands, metal-cutters and crowbars to reach more survivors who shouted through drainage pipes and holes cut in the concrete. One person called a relative using a cell phone and said that he was alive under the concrete-and-steel rubble.
Officials at the scene called the rescue efforts risky and chaotic. Hands of those waiting to be rescued could be seen waving from beneath the rubble, reports CBS' Alison Harmelin.
Tens of thousands of people ran to the site, clogging the roads and climbing on top of the rubble to watch the rescue. Riot police deployed to the area and beat back crowds with truncheons, clearing roads for emergency vehicles.
President Mwai Kibaki announced he was cutting short an official visit to Sudan in order to coordinate rescue efforts, according to a statement.