In Aden, Yemen's second city, seven civilians died and 94 were wounded after Shiite Huthi rebels fired rockets on neighbourhoods controlled by troops loyal to exiled President Abedrabbo Mansour Hadi, the city's health chief Al-Khader Laswar told AFP.
The fire destroyed several houses, according to Aden vice-governor Nayef al-Bakri.
Further north in Dhaleh, fierce clashes between Huthi fighters and loyalist troops killed 24 rebels and eight in the pro-Hadi camp, including a local commander, a local official said.
Fighting has dragged on for several months in Aden, where Iran-backed Shiite rebels have battled pro-Hadi loyalists since the president fled to Riyadh in March.
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A Saudi-led coalition has been pounding rebel positions in Yemen since March 26, following a Huthi advance from their northern stronghold into the capital Sanaa, and a subsequent push south towards Aden.
More than 2,600 people have been killed in Yemen since March, according to UN figures, and almost 80 percent of the population -- 20 million people -- are in need of urgent humanitarian aid.