Startling before and after photographs reveal the devastating floods in Houston as Hurricane Harvey swamps the city, destroying thousands of homes and prompting the mayor to plead for help

Huge swathes of the city now sit underwater as flood water continues to rush through its streets. Thousands are without homes, even more have lost power and the death toll - which is expected to rise - is feared to be five. There is no respite on the horizon, with another 50 inches of rain scheduled to land over the course of the week. Emergency services have been pushed to the limit. 911 operators are having to choose between life-fearing callers and panicked residents are clambering to their roofs to wave towels in the hope that someone will rescue them. Here, in a collection of photographs taken around the city before and after the storm hit, the scope of the damage is laid bare. There were 5,500 people in shelters on Monday morning and 911 operators had responded to 75,000 calls alone by 10.30am.