The United Nations says one of its staff members was killed and another injured as they travelled to a hospital in southern Gaza on Monday.
India's mission to the UN in New York named the staff member as Col Waibhav Kale, who worked for the UN Department of Safety and Security (UNDSS) in Gaza.
The UN said the workers were travelling in a UN vehicle to the European Hospital near Rafah when it was struck.
It did not mention who it thought was responsible for the attack.
The UN says the death is the first of an international UN worker in Gaza since the start of the conflict.
The Israeli military said an initial inquiry indicated the vehicle was struck in an active combat zone and it had not been made aware of its route.
But the UN said the vehicle was clearly marked and its planned movements had been announced in advance to Israeli authorities.
Rolando Gomez, a UN spokesman in Geneva, said the UN informs Israeli authorities of the movement of all its convoys in Gaza.
"This is a standard operating procedure. That was the case yesterday morning," Mr Gomez said told a news briefing.
Footage posted on social media and verified by the BBC shows a marked UN vehicle with multiple bullet holes outside the European Hospital.
The Israel Defense Forces (IDF) confirmed it had received a report from the UNDSS that said two of its workers were injured in the Rafah area - in southern Gaza - on Monday.
The IDF added that the incident was under review.
India's mission to the UN in New York said its "deepest condolences are with the family" of Col Kale, who Indian media reports was a former member of the Indian army.
UN secretary-general António Guterres said he was "deeply saddened" to learn of the worker's death and sent his condolences to their family, his spokesman Farhan Haq said in a statement.
"The secretary-general condemns all attacks on UN personnel and calls for a full investigation," Mr Haq added.
In a separate statement, Mr Guterres said more than 190 UN staff had been killed in Gaza since the war began.
While Col Kale is the first international casualty for the UN, six international aid workers and a Palestinian colleague from the international food charity World Central Kitchen were killed in an Israeli strike at the start of April.
Their deaths sparked an international outcry and the IDF sacked two senior officers over the incident which it described as a "grave accident".
Israel launched a military campaign in Gaza with the stated aim of destroying Hamas - which controls Gaza - in response to the group's cross-border attack on southern Israel on 7 October, during which about 1,200 people were killed and 252 others were taken hostage.
More than 35,090 people have been killed in Gaza since then, according to the territory's Hamas-run health ministry.
