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.
It said the workers were travelling in a UN vehicle to the European Hospital near Rafah when it was struck.
The UN did not mention who it thought was responsible for the attack.
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.
The Israel Defense Forces (IDF) confirmed it had received a report from the UN Department of Safety and Security (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.
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 start of the conflict.
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.
