This is the terrifying moment commuters were sent crashing down an escalator as it suddenly changed direction and hurtled backwards at breakneck speed.

The horrifying ride was caught on CCTV footage at the Ucyol Metro Station in Izmir, Turkey, on July 1 while it was packed with rush hour passengers.

As the up escalator brought passengers to the surface from the platforms, it suddenly lurched to a stop as they clung to the handrails trying to keep their balance.

Then without warning the moving stairway suddenly reversed itself taking the passengers downhill backwards at more than twice the usual speed.

As they fell backwards they crashed into each other tumbling down the staircase in a heap and landing in a pile of sprawled bodies at the bottom.

Local media reports say paramedics rushed 11 passengers to the hospital where they were treated for their injuries and allowed home.

According to city officials, the escalators at the metro station were serviced the day before the incident.

The Izmir Metropolitan Municipality said in a statement: 'The service and maintenance of the escalators at Ucyol Metro Station were conducted on June 30, one day before the malfunction occurred.'

It added that repair work has since been carried out.

Police and railway safety inspectors are investigating the crash.