Transport for London described it as “a new river” on Kennington Park Road, resulting in huge traffic delays and disruption to several bus routes, including diversions for routes 3, 59, 133, 155, 159, 333 and 415.
"We're working as fast as we can to stop the flooding.
"Kennington Park Road is currently closed in both directions between Kennington Oval and Kennington Station, diversions are in place.
"We apologise for any inconvenience this has caused."
Darren Merril, cabinet member for environment and public realm at Southwark Council, added:"Our main priority is still identifying and assisting any vulnerable residents who may still be experiencing difficulties while full repairs are carried out and water is restored. Two libraries and nine schools in Southwark have closed.
"We know what an inconvenience this is for many people, especially in this hot weather, and Thames Water has assured us they are doing all they can to fix the pipe.”