An Israeli air strike on a Gaza hospital Sunday killed four people and wounded 17, WHO chief Tedros Adhanom Ghebreyesus has said, AFP reports.

The strike at Al-Aqsa hospital was witnessed by a World Health Organization team sent there to assess needs and to collect incubators for the north of Gaza, Tedros said in a post on X, formerly Twitter.

Israel’s military denied that the hospital was damaged.

“A WHO team was on a humanitarian mission at Al-Aqsa Hospital in Gaza, when a tent camp inside the hospital compound was hit by an Israeli airstrike today,” the WHO chief wrote.

He gave no details of the victims, but added: “WHO staff are all accounted for.” The Israeli army said on X that one of its planes “struck an operational Islamic Jihad command center and terrorists positioned in the courtyard of the Al-Aqsa Hospital in the area of Deir al Balah.

“Following the precise strike, the Al-Aqsa hospital building was not damaged and its function was not affected,” it added.

Tedros said in a later post that 21 patients had died at Al-Shifa hospital in the northern Gaza City since March 18.

The hospital, which was Gaza’s largest before the conflict broke out, has only one bottle of water available for every 15 people, he said.