The United Nations headquarters in the Gaza Strip came under Israeli attack today.
The compound has been serving as a shelter for hundreds of people fleeing Israel's devastating offensive in Gaza. A UN spokesman said at least three people were wounded.
The compound includes the headquarters of the UN agency for Palestinian refugees, other offices and a school.
The attack came as UN chief Ban Ki-moon was in Israel trying to promote a cease-fire.
He expressed "strong protest and outrage" to Israel over the shelling and demanded an investigation.
He said Israeli Defence Minister Ehud Barak told him it was a "grave mistake".
The al-Quds hospital in the Tel al-Hawa neighbourhood is also reportedly on fire and a building housing several central media outlets, including the Reuters news agency, was also hit. Two journalists were said to be seriously wounded. Another press building was also struck.
Israeli forces said they had pushed deeper into Gaza City amid heavy fighting, with some units within a mile of the densely populated urban centre. Terrified residents were said to be fleeing from many homes which had been set alight.