At least one person was killed and several injured when a four-storey shopping centre under construction collapsed in Nigeria's capital, Abuja.
Emergency workers are trying to rescue as many as 15 people believed to be buried beneath the rubble.
Several others were pulled out alive. Rescuers are reported to be talking by mobile phone to a construction worker trapped inside the wreckage.
The building site was due to become the capital's largest shopping centre.
Eyewitness Mustapha Murtala told the BBC that there were about 20 labourers working on the building as it collapsed.
Reuters news agency quoted police as saying the number was between 40 and 50.
"There was a woman selling water in the building, she started screaming and the building collapsed," Mr Murtala said.
He said she was killed by falling debris.
The BBC's Andrew Walker in Abuja says building collapses have been common in Nigeria.
Two years ago the government promised to improve building regulations after hundreds were killed when a high-rise building collapsed in Nigeria's main city of Lagos