Firefighters assisted police at an incident on Daneby Road in Catford.
The Brigade was called to assist following a report that an individual was inside a property in possession of a gas canister. Surrounding properties were evacuated by emergency services.
The Brigade committed several resources to the incident including pumping appliances and fire and rescue units. At least one Command Unit was always present at the incident which helped relay information from the scene to Control officers.
After over 50 hours of engagement and negotiations, the incident was concluded safely.
London Fire Brigade Assistant Commissioner Thomas Goodall said: "This was an extremely sensitive and complex incident in which London Fire Brigade responded and provided around-the-clock support to the Metropolitan Police and other multi-agency partners.
"Commanders and specialist crews provided advice at the scene, in order to help bring this incident to a safe conclusion. Together with frontline crews, the Brigade was also on standby ready to respond immediately in the event of any escalation.
"Throughout the incident, Control officers and commanders ensured crews were available to respond to other incidents and emergency calls in the surrounding area."
The Brigade was called at 1842 on 25 March and the incident was over for firefighters by 0328 on 28 March. Crews from parts of south east and south London attended the scene.