Firefighters and volunteers rescue passengers trapped by deep rain waters in Beijing, on July 21, 2012. The heaviest rain in 61 years that lashed Beijing Saturday have left at least four people dead and six others injured, local authorities said. The heavy rain that began to thrash the city around 10 am on Saturday inundated roads, making some impassable, and severely disrupted air traffic.[Photo/Xinhua]

A military training base is trapped by waters before all the 350 students and 40 teaching staff trapped were relocated in Fangshan district of Beijing, on July 21, 2012. [Photo/Xinhua]

A citizen wades through on a flooded street in Beijing, on July 21, 2012. [Photo by Zhu Xingxin/China Daily]

Cars are submerged in a flooded road in downtown Beijing in the evening on July 21, 2012. [Photo/Xinhua]

Flood control people drain off waters on a flooded road in Beijing in the evening on July 21, 2012. [Photo/Xinhua]

Pedestrians wade through in rain waters carrying a baby carriage in an underground passage near the Beijing West Railway Station, on July 21, 2012. [Photo/Xinhua]

Students trapped by waters in a military training base are evacuated in Fangshan district of Beijing, July 22, 2012. There was no casualty in the base. [Photo/Xinhua]

A student from a military training base in Fangshan district of Beijing shows his shoes after one night's downpour, on July 22, 2012. [Photo/Xinhua]

Cars wait for rescue after flood recedes in Beijing, on July 22, 2012. [Photo/Xinhua]

Rescuers and residents stand next to a stranded car which is being pulled up from a flooded street under the Guangqumen overpass amid heavy rainfall in Beijing, July 21, 2012. [Photo/Agencies]