The World Health Organization (WHO) has strongly condemned an apparent attack on a hospital in northern Gaza on Tuesday that has reportedly left many hundreds of people killed and injured. 

An Israeli airstrike struck al-Ahli Arab hospital in Gaza City, international media reported, citing the Health Ministry in the Hamas-controlled enclave.

The details have yet to be verified, but the Israeli Defense Forces tweeted that according to its intelligence information, rockets fired by Islamic Jihad militants towards Israel were to blame, having deviated off course.

Patients and displaced civilians were reportedly seeking shelter at the hospital, following Israel’s order to evacuate to the south in advance of what is expected to be a ground assault.

“WHO strongly condemns the attack,” agency chief Tedros Adhanom Ghebreyesus wrote in a post on the social media platform X, formerly known as Twitter. 

“We call for the immediate protection of civilians and healthcare, and for the evacuation orders to be reversed,” he added. 

Evacuation order 'impossible to carry out'

Al-Ahli Arab Hospital was operational, with patients, health and care givers, and internally displaced people sheltering there, WHO said in a statement.

It was one of 20 hospitals in the north of the Gaza Strip facing evacuation orders from the Israeli military.

"The order for evacuation has been impossible to carry out given the current insecurity, critical condition of many patients, and lack of ambulances, staff, health system bed capacity, and alternative shelter for those displaced," WHO said.

The UN agency appealed for the immediate active protection of civilians and healthcare. "Evacuation orders must be reversed. International humanitarian law must be abided by, which means health care must be actively protected and never targeted."

The UN Population Fund (UNFPA) also took to social media to condemn the attack.

"Attacks on civilians and civilian infrastructure must cease, and healthcare facilities must never be a target," the UN's reproductive and sexual health agency posted on X.

UNRWA school hit

Earlier on Tuesday, the UN agency that assists Palestine refugees across the Middle East, UNRWA, reported that at least six people were killed when one of its schools was hit in al-Magahazi camp, located in Gaza’s middle area.

Dozens more were injured, including staff from UNRWA staff, and numbers are likely to be higher.

“This is outrageous, and it again shows a flagrant disregard for the lives of civilians. No place is safe in Gaza anymore, not even UNRWA facilities,” the agency’s Director-General said in a statement.

At least 4,000 people had sought refuge in the school-turned shelter. “They had and still have nowhere else to go,” UNRWA said.