The United Nations children's agency UNICEF said on Friday it was "outraged" after two truck drivers it contracted to deliver clean water to families in the Gaza Strip were killed by Israeli fire.
The UN agency said in a statement the incident occurred during routine water trucking Friday morning at the Mansoura water filling point in northern Gaza, which supplies Gaza City. Two others were injured in the attack.
UNICEF said it had suspended activities at the site and called on Israeli authorities to investigate, stressing that humanitarian workers, civilians and vital water infrastructure must be protected under international humanitarian law.
Israel's embassy in Washington didn't immediately respond to a request for comment.
October's ceasefire in Gaza halted two years of full-scale war but left Israeli troops in control of a depopulated zone that makes up well over half of Gaza, with Hamas in power in the remaining, narrow, coastal strip.
More than 750 Palestinians have been killed since then, according to the enclave's health authorities.