The United Nations called Monday for investigation into the deaths of scores of civilians including schoolchildren in the Yemeni capital on Sunday.
The UN Humanitarian Coordinator for Yemen Lise Grande sent condolences to victims' families, voicing alarm at the "terrible, senseless deaths and injuries."
"Every effort must be made to understand the circumstances that led to this tragedy," she added.
"Protecting people and protecting civilian infrastructure are core principles of international humanitarian law. Even as we are struggling to address the worst food security crisis in the world and one of the worst cholera outbreaks in modern history, these principles are being violated" in Yemen, said Grande.
The most vulnerable people, who most need our assistance, need also greater part of our sympathy, since they are the most ones who pay high price of this conflict, she added.
Yemen has been racked by an armed conflict that broke out after the Iranian-backed Houthis had ousted the internationally recognized government late in 2014.
The conflict escalated after a Saudi-led coalition intervened militarily in the country in March 2015 to reinstate the government of President Hadi.
Warring parties have traded blames for the incident, with Houthi group accusing a Saudi-led coalition airstrike on residential area in Sawan, and the coalition denyingand shifting the blame onto the rebels.
The incident was resulted from an explosion at Houthi bomb workshop, coalition spokesman Turki al-Maliki added, claiming that their aircraft had not targeted populated areas.
The United Nations said Sundayit was worried as following the blast that left civilian casualties in Sana'a.
A large explosion at warehouse in the Yemeni capital on Sunday reportedly left at least 13 people killed, including 7 children, and more than 100 injured, UN spokesman Stephane Dujarric added, calling on all parties to practice maximum restraint and ensure safety of all Yemenis.
The conflict has triggeredwhat the UN calls the world's worst humanitarian crisis, with most of the population in need for a type of humanitarian aid and immediate protection, including 14 million people risking famine and some 1.8 million children suffering malnutrition.