A nurse working to contain Ebola in the Democratic Republic of Congo was hacked to death by a group of young attackers wielding machetes, officials said.
Another health worker was injured in the same ambush in a remote part of Tshopo province on Friday but lived after police rescued him.
Authorities warned the brutal assault may be the latest episode in a rising tide of violence against medical staff, driven by unfounded online conspiracy theories.
The unnamed victims were surrounded by the youths, who carried machetes and batons, and were accused of deliberately contaminating the water supply with the virus.
Last month, a Congolese politician was beaten to death by a gang after urging the public to follow response measures such as social distancing and regular hand washing.
Recent attacks have also targeted hospitals, ambulances and medical personnel, with false rumors on social media blaming doctors for the outbreak.
Other conspiracies claim the epidemic is a money-making hoax for aid agencies or a pretext for foreigners to seize the country's mineral resources.
The slain nurse was stationed at the general hospital in Bafwasende, serving on the frontline of an outbreak that the DRC health ministry says has claimed more than 4,800 lives since May.
The killing was condemned by several international bodies, including the World Health Organization and the United Nations.
WHO Director-General Tedros Adhanom Ghebreyesus said: "Everyone working to protect communities from this deadly disease must be able to work in dignity and safety. Healthcare must always be protected."
WHO Africa regional director Dr Mohamed Yakub Janab added: "Misinformation and fear must never fuel violence."
UN senior Ebola coordinator Julien Harneis called the murder a "loss to the Ebola response and an even greater loss to patients."
The incident follows a recent Ebola death in Kenya, the country's second-ever fatal case.
A 65-year-old woman, a close relative of Kenya's first victim, died after developing symptoms while in quarantine.
The first Kenyan case, a 40-year-old man, died in Nairobi late on Monday after traveling from the DRC, the centre of the current epidemic.
He had shown symptoms for two weeks and was treated at an infectious disease unit in Nairobi.
Kenya's health ministry said medics did everything possible, but the woman died Friday evening.
Seven Ebola patients remain in two isolation facilities, and no new infections have been reported.
All cases are within "one cluster, with no evidence of community spread," the ministry said.
The man who died on October 5 was Kenya's first recorded Ebola case, prompting a hunt for dozens of possible contacts.
Authorities identified about 135 contacts and placed 118 under lockdown.
Eight of those contacts tested positive while in quarantine, including the latest victim, four health workers and three family members.
Kenyan border points are on high alert amid fears the virus could spread further.
Officials urged Kenyans "not to panic, as all systems are in place to mitigate the spread of the disease."
The outbreak continues to sweep through eastern DR Congo at a rapid pace, with health workers battling what one expert called a viral "megafire".
France has also recorded a case during the current outbreak.
Nigeria reported its first Ebola patient, the wife of a Swiss diplomat, who tested positive after returning to Abuja from Uganda.
