The mine, planted on a road in the Hays district, exploded when civilians were passing by, according to local sources.
Its explosion left Halil Vahib, 12, Sabir Mashur, 15, Mustafa Ashebi, 35, dead, and injured another 12-year-old child, Andalou reported.
A separate blast that occurred in the southern city of Abyan killed one and injured five members of the forces of the separatist Southern Transitional Council (STC).
According to previous statements by Yemeni officials, more than 2 million landmines dot the war-torn country.
Since March 2015, Saudi Arabia and some of its Arab allies have been carrying out deadly airstrikes against the Houthi Ansarullah movement in an attempt to restore power to fugitive former president Abd Rabbouh Mansour Hadi, a close ally of Riyadh.
The war has killed tens of thousands of people, mostly civilians, and resulted in what the UN has described as the world's worst humanitarian crisis.
The children are among tens of thousands of Yemenis, who have died since March 2015, when the kingdom and its allies began taking the Arab world’s poorest nation under a wholesale war.
The fatalities have, in part, been caused by the coalition’s application of Western-provided precision ammunition on crowded civilian centers and residential areas.
SKH/PR