UNRWA said two tank shells hit the training college in the west of the city, where 800 people were sheltering.

Israel has not commented specifically on the blasts but said its forces were operating in the surrounding area.

Its troops have encircled the city and ordered people still there to leave.

UNRWA’s Gaza director, Thomas White, said on X, formerly Twitter, that its Khan Younis Training Centre had been hit during fighting and added that there were “mass casualties”.

Several people have been killed after a United Nations shelter in Gaza‘s southern city of Khan Younis was shelled by Israeli forces, the Gaza head of the UN agency for Palestinian refugees has said.

“Two tank rounds hit building that shelters 800 people – reports now 9 dead and 75 injured,” Thomas White, the Gaza director of the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA), said on the social media platform X.

In a separate post earlier on Wednesday, White said the training centre sheltering displaced families had been set ablaze.

The number of victims is expected to rise, as the UN official said the incident had likely caused “mass casualties”.

UNRWA spokesman Adnan Abu Hasna, based in Rafah, told Al Jazeera the UN has been trying to send ambulances to the site in coordination with the Israeli army.

He said no warning had been issued by the Israeli military prior to the attack.

The agency has not been able to access the compound for the past 48 hours due to the presence of Israeli tanks in the area, Abu Hasna said, describing the situation as “very dangerous”.

We tried to coordinate the exit of the IDPs [internally displaced persons] there but did not succeed unfortunately,” he added.

Philippe Lazzarini, the head of UNRWA, condemned the attack on the shelter as “a blatant disregard of basic rules of war”.

“The compound is a clearly marked UN facility & its coordinates were shared with Israeli authorities as we do for all our facilities,” he wrote in a post on X, saying the number of those killed is likely higher.

‘Fire everywhere’

Israel has continued intense attacks on Khan Younis, targeting medical facilities, among others. Some 660 attacks on health institutions have been recorded in Gaza.

Gaza’s Ministry of Health on Wednesday said the Israeli army isolated the Nasser Medical Complex in Khan Younis after it was encircled and ground troops engaged in close-quarter combat with Hamas fighters

He told CNN that the blasts struck a carpentry building after two days of fighting around the centre, when UN staff had been unable to get there.

“We are in constant contact with the Israeli army, who have been giving assurances that people in protected facilities… are safe,” he added.

“The reality is that lives have been taken in and around these facilities in the last couple of days.”

It comes as fierce fighting rages in southern Gaza, including in the densely populated refugee camp within Khan Younis, which is in close proximity to the UNWRA training centre.

The IDF said Israeli forces were “located around the camp, in the western part, and have begun to operate within it”.

It said they were part of a “divisional manoeuvre” around western Khan Younis to dismantle “Hamas’ military framework”.

“The manoeuvre will continue against military targets that are in the area, outposts, infrastructure, and command and control centres,” it said, adding that Hamas “exploited” the densely populated area, as well as its shelters and hospitals.

The Hamas-run Gaza health ministry said more than 200 Palestinians had been killed in the past 24 hours, amid some of the heaviest fighting yet seen in the Israeli campaign to destroy Hamas.

Israel launched its invasion of Gaza days after Hamas killed more than 1,300 people and took more than 250 hostages in its 7 October attacks inside Israel.

More than 25,700 people have been killed in Gaza since then, according to its health ministry