Liberian authorities introduced a nationwide curfew and put the neighbourhood - West Point - under quarantine. The rundown area has been hit by Ebola, which has killed more than 1,200 people in four West African countries.
President Ellen Johnson Sirleaf declared a curfew and ordered security forces to quarantine the district which is home to at least 50,000 people as the country fought to stop the spread of Ebola in the capital.
At least 1,229 people have died of Ebola in Guinea, Liberia, Sierra Leone and Nigeria in the current outbreak, and more than 2,240 have become ill, according to the World Health Organisation.
The fastest-rising number of cases has been reported in Liberia, with at least 466 dead.
The authorities have struggled to treat and isolate the sick, in part because of widespread fear that treatment centres are places where people go to die.
Many sick people have hidden in their homes, relatives have sometimes taken their loved ones away from health centres and mobs have occasionally attacked health workers.
Ms Sirleaf said: "We have been unable to control the spread."