Israeli forces stormed several WHO facilities during their latest advance in the Gaza Strip, Director-General Tedros Adhanom Ghebreyesus said in a statement on Monday.
The facilities were attacked three times, according to Ghebreyesus.
He said, "Israeli military entered the premises, forcing women and children to evacuate on foot toward Al-Mawasi amid active conflict."
"Male staff and family members were handcuffed, stripped, interrogated on the spot and screened at gunpoint. Two WHO staff and two family members were detained. Three were later released, while one staff member remains in detention."
The WHO is calling for the staff member's release.
Tedros said that the main WHO warehouse, located in Deir al-Balah, was also damaged.
"As the lead agency for health, compromising WHO's operations is crippling the entire health response in Gaza," Tedros said. "A ceasefire is not just necessary, it is overdue."
WHO stated it will remain in Deir al-Balah and continue its operations despite the attacks.
Israel's army did not initially comment on the incidents.