Eight civilians including five members of one family were killed in 24 hours of shelling by Iran-backed rebels on residential parts of Yemen's third city Taez, local officials said Monday.
Three children were among those killed in clashes that have continued despite a ceasefire and peace talks in Kuwait between Houthi rebel and loyalist delegates, the sources said.
Another 13 civilians were wounded, the sources added, accusing the rebels of firing mortar and artillery rounds into the residential areas.
Rebel shelling of the besieged government garrison in Taez killed 11 civilians on Saturday, drawing condemnation from UN envoy Ismail Ould Cheikh Ahmed.
He has urged both sides to respect the ceasefire that took effect on April 11.
However, the government sources in Taez said nine loyalist fighters were killed and 26 wounded in 24 hours of clashes in the city's eastern districts.
Military sources told AFP that 12 rebels were also killed.
Witnesses said fighting continued on Monday across several residential neighbourhoods of the southwestern city.
Separately, suspected militants attacked the airport in the government-held second city Aden, sparking a firefight that killed at least one civilian, a security source said.
Around 20 gunmen stormed the main entrance road to the airport in the city's Khormaksar district, demanding the release of a fellow militant of Western origin who was detained late last month.
Airport guards repulsed the attack after a 90-minute battle, the source said, adding that the civilian was killed by a stray bullet.
The gunmen's leader told security forces he was a close relative of the detained militant, a Western national of Algerian origin.
The detained Westerner was among seven suspected members of the Islamic State (IS) group whose arrest was announced by the authorities in Aden on May 28.
Aden is the headquarters of the Saudi-backed government of President Abdrabbo Mansour Hadi since the capital Sanaa and swathes of the north and centre of the country are held by the Shia Houthi rebels and their allies.
In the neighbouring province of Abyan, a gunman on the back of a motorbike killed the commander of a loyalist army brigade late on Sunday, a security official said.
Colonel Mohammed Salem al-Abbadi was one of the founders of the pro-government militias that drove Al-Qaeda out of Abyan in 2012.
Saudi Arabia led a military intervention against the rebels in Yemen in March last year, and the ensuing conflict has been exploited by IS and rival Al-Qaeda militants to expand their presence in the impoverished Arab nation.
In recent months, Saudi-led forces have taken action against the militants with US support, driving them out of several southern cities they had overrun.