From the BBC:
Dubai's economy has boomed in recent years, fuelled largely by a construction industry reliant on low-paid workers, many from South Asia. The labourers were employed by the Wade Adams Group, a contracting company based in the Middle East.
More than 40 people were working on the bridge at the time of the collapse, police said. Fifteen injured workers were admitted to Dubai's Rashid hospital, according to hospital officials.
Five who had serious injuries were airlifted to the hospital.
"We tried to put a huge piece of metal in a wall when it collapsed," said Muthu Raj, one of the workers interviewed by the media. "I saw colleagues trapped inside, but I managed to jump back and stepped on the road."
These migrant workers are working under extremely dangerous conditions for many hours a day despite the low payments they receive. There are hardly any real and effective efforts being made towards their security or at least an increase in workers' salary in Dubai and the rest of the Gulf where these incidents are not uncommon.