Officials from the World Health Organization are visiting two hospitals treating Ebola patients in Liberia, where authorities have sealed off entire neighborhoods in an effort to stop the outbreak, AP reported. After clashes between protesters and security forces in the sealed-off slum of West Point, calm returned Thursday. A nationwide nighttime curfew appeared to have been put in place without major incident. Ebola has killed more than 1,300 people in Liberia, Sierra Leone, Guinea and Nigeria. The disease is spreading fastest in Liberia, and authorities there have resorted to the most severe measures. On Wednesday, they sealed off West Point and another densely populated town.