Firearms officers have arrested six people at an address in Catford after an attempted armed robbery at a local supermarket.
The robbery took place just after 13:00 on Friday at Catford Broadway, with roads in the area swiftly being closed.
Officers traced a suspect to a nearby address, where six arrests were made.
Reports of gunfire appeared on social networking site Twitter, but a police spokesman said he had no official confirmation that shots had ben fired by either officers or suspects.
The A205 south circular road was closed between Ravensbourne Road and Canadian Avenue for at least two hours.
Additional reporting: Chris Stevenson