"Preliminary reports are that the IDP (internally displaced) families were trying to flee hostilities from elsewhere in Taiz", a spokesperson said.
Saudi Arabia and its allies have blockaded Yemen since the start of the war, and while they've allowed humanitarian aid into the southern parts of the country they control militarily, they've heavily restricted shipments further north, into the Shi'ite-controlled half of the country.
"It also illustrates the difficulties in the delivery of humanitarian protection and assistance in Yemen", Spindler added.More news: New Street Fighter V Character Announced: Abigail from Final Fight
A coalition of Arab countries assembled by Saudi Arabia launched an air campaign against the rebels in March 2015 to try to restore the internationally recognised government of President Abd-Rabbu Mansour Hadi to power.
The Saudi-led coalition has faced repeated criticism over civilian casualties in Yemen.
Saudi Arabia is using British-manufactured weapons in the offensive, sparking failed legal challenge by the Campaign Against the Arms Trade in the High Court.
Dr Abdullah al-Rabeeah, a former Saudi minister and now head of the country's state aid agency, told The Independent "there is no intention whatsoever to bombard or kill civilians".More news: Kids' apparel retailer Gymboree closing 16 IL stores
"The coalition suspended the United Nations flight leaving Djibouti for Sanaa on Tuesday as there were three BBC journalists on board", Saleh Humeidi, a top official with Yemen's Information Ministry, told AFP.
Yemen's conflict has pushed seven million people to the brink of starvation, according to the UN. The coalition shut down Sanaa's global airport a year ago.
"It is necessary to work closely to contain the cholera epidemic and prevent its outbreak in more Yemeni provinces and cities to avoid a possible humanitarian crisis whose consequences may last for years to come", said the AL chief in the statement.
Those killed in the airstrike were among the more than two million internally displaced Yemenis "who have fled elsewhere across Yemen since the beginning of the conflict, but continue to be exposed to danger as the conflict has affected all of Yemen's mainland governorates", the United Nations.More news: Celtic and Linfield could potentially face tough sanctions from UEFA