U.N. Secretary General Ban Ki-moon has denounced an attack on a U.N. convoy that killed at least one person in the Gaza Strip on Thursday.

Ban’s spokesman said in a statement that the secretary-general condemns the firing on a U.N. aid convoy in Gaza by the Israeli Defense Force.

The statement also said that the U.N. is in close touch with Israeli authorities about a full investigation into this and other incidents, as well as the need for urgent measures to avoid similar happenings in the future.

The statement added that the secretary-general is calling once again for an immediate ceasefire in order to facilitate full and unhindered humanitarian access, and to allow aid workers to work safely when trying to reach persons in need.

Two tank shells hit a truck convoy on its way to pick up U.N. assistance in northern Gaza, killing the convoy’s driver.