A UN official has said he is deeply disturbed by reports that 30 people were killed in Saudi-led coalition air strikes on a well in Yemen on Saturday.
The casualties from the incident in Beit Saadan included first responders and children, according to humanitarian co-ordinator Jamie McGoldrick.
Witnesses said warplanes first bombed workers drilling for water, then hit a crowd gathered at the scene.
The coalition said all its operations in the area had targeted Houthi rebels.
The UN says more than 10,000 civilians have been killed or wounded since the coalition launched a campaign in March 2015 to defeat the rebels and restore Yemen's internationally-recognised government.
Residents of Beit Saadan, a rebel-held village in the Arhab district north of the capital Sanaa, said coalition warplanes targeted workers drilling for water on Saturday, apparently mistaking their machinery for a rocket-launcher.
When locals rushed to the scene to help the victims, the aircraft returned and bombed the site again, killing and injuring more people, they added.
Yemen's official Saba news agency, which is controlled by the rebels, reported that were more than 100 casualties.
"I remain deeply disturbed by the unrelenting attacks on civilians and on civilian infrastructure throughout Yemen by all parties to the conflict, which are further destroying Yemen's social fabric and increasing humanitarian needs, particularly for medical attention at a time when the health sector is collapsing," Mr McGoldrick said in a statement on Monday.
He called on all parties to uphold their obligations under international humanitarian and human rights law and recommit to the cessation of hostilities negotiated by the UN in April ahead of peace talks that collapsed last month.
Mr McGoldrick noted that intensified fighting since then had seen several missile attacks on Saudi Arabia. On Monday, the coalition said Saudi air defence forces had shot down a ballistic missile launched towards the city of Khamis Mushait.