Security alarms were heard loudly ringing for at least two hours in several buildings following the vandalism attacks.
Residents were warned to stay indoors as the "opportunistic" youths, most of them wearing hoods or masks, held little regard for the law.
The train station, Clapham Junction, is known as "Britain's busiest train stations".
A few miles south are dozens of middle class and wealthy families in million pound homes.
Just after midnight police told residents to evacuate after a local fancy dress shop and flats above it were set on fire.
The blaze on Lavender Hill sent plumes of smoke up into the air amid fears that helium canisters could explode.
We have been making arrests all evening and have a team working during the night examining CCTV images.
"We will follow up evidence in the coming days in order to bring anyone else responsible for criminal acts to justice." The area, one of the most popular in south London, resembled a ghost town instead of the bustling hive of activity on a Monday night.
"We don't want people getting hurt by their bombs and missiles," said one officer.
"There was no rhyme or reason, it was just anarchy," said one resident, who gave his name as Tim.
"They were just out to cause trouble." As a result of the lawlessness, the Metropolitan Police introduced "additional tactics using armoured police vehicles to push back" locals.
Earlier, looters had stolen masks from the fancy dress store to hide their identity.
At first police had the area in lockdown at rush hour as commuters were faced with dozens of masked youths. We couldn't go anywhere," he told officers, his head in hands, and body shaking.Looters had stolen masks from a fancy dress store to hide their identity.