At least 43 people were killed and 100 were wounded near Yemen's second city of Aden on Sunday, in what officials said was shelling by Houthi rebels.
The militia has been fighting for control of Aden in recent months, as it clashed with forces loyal to the internationally recognized government.
A Saudi-led coalition began an air campaign in the country four months ago in support of exiled President Abd Rabbu Mansour Hadi, now living in Riyadh.
The Houthis stoked internal political divisions in Yemen late last year, ultimately pushing the president out.
Violence on the ground paired with the ongoing airstrikes have killed at least 1,670 civilians since March, the United Nations reported last week.
With commercial flights cancelled, the relentless conflict has pushed thousands of Yemenis to flee the country by land and sea.