The World Health Organization has suspended medical evacuations from Gaza to Egypt after a "security incident” in which a contract worker was killed, an episode Israel said Tuesday involved its soldiers opening fire in response to "an immediate threat.”

WHO chief Tedros Adhanom Ghebreyesus on X late Monday wrote that the U.N. health agency was "devastated to confirm that a person contracted to provide services to the organisation in Gaza was killed today during a security incident."

Two staff members who were also present were not injured, he added.

WHO did not elaborate, but said the incident was "under investigation by the relevant authorities."

Israel's mission in Geneva, meanwhile, posted on X Tuesday that a day earlier in southern Gaza, "IDF troops identified an unmarked vehicle approaching them and posing an immediate threat," it said, stressing that "troops fired warning shots" in response.

"The vehicle continued to accelerate toward the troops, who then responded with additional fire, and a hit was identified," the post said, adding that "the incident is under review."

Tedros said that the WHO had suspended "medical evacuation of patients from Gaza via Rafah to Egypt" that had been planned for Monday.

"Medical evacuations will remain suspended until further notice," he said.

"We call for the protection of civilians and humanitarian workers."

Israel and Hamas have accused each other of repeatedly violating the ceasefire that came into force on Oct. 10 in the Gaza Strip, after two years of Israel's genocidal war.