Wooden decking on a railway bridge near Elephant & Castle caught fire on Sunday evening, sending hot ashes onto a pavement where pedestrians were walking.
Firefighters from Lambeth and Old Kent Road stations tackled the blaze in Hampton Street.
At first, fire crews monitored the blaze from the platforms of Elephant & Castle Railway Station before they were alerted to the risk to the public in nearby Hampton Street.
The crews had to wait for Network Rail to turn off the power supply before they could fight the flames.
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