A yet-unidentified illness has killed 53 people and potentially infected hundreds more in the Democratic Republic of the Congo. The World Health Organization is investigating the outbreak.

Dozens of people have died and hundreds have become sick after an unknown illness appeared in Congo’s northwestern Equateur province, WHO spokesperson Tarik Jasarevic said Tuesday during a UN briefing.

A mysterious disease outbreak in the Democratic Republic of Congo has claimed over 50 lives, with symptoms resembling haemorrhagic fever. The illness, which reportedly spreads rapidly and leads to death within 48 hours,