Two car bombs killed at least 31 people , including 20 children , in central Yemen 's Radaa city when suspected al Qaeda fighters targeted Houthi militants Tuesday , senior security officials and locals told CNN . One car bomb struck a Houthi gathering point , but the other did not make it to the target and instead blew up next to a bus that was carrying children home from school , officials said . All the killed children were under the age of 12 , said Osama Sari , a prominent pro-Houthi activist . Eleven Houthi fighters were killed , an Interior Ministry official said . Eyewitnesses told CNN that the death toll within Houthi lines exceeded 18 . At least a dozen others were injured , among them six in critical condition , medical sources in Radaa told CNN . Radaa was an al Qaeda stronghold that fell to Houthi fighters after clashes in October that killed hundreds from both sides . Al Qaeda has since intensified its attacks on Houthi targets , conducting daily attacks killing hundreds of Houthis and innocent civilians . Houthis follow the Zaidi sect of Islam and are considered Shiite Muslims by al Qaeda , a Sunni Muslim terrorist network . Sari said that most of the killed were children and that the attack holds the hallmarks of al Qaeda . `` The suicide car bombs were supposed to directly hit the Houthi camp . When they failed to reach the core target , many innocent children lost their lives , '' Sari said .
One car bomb hit Houthi militants ; another exploded next to a school bus , officials say . Both bombs , apparently from al Qaeda fighters , were meant for Houthi militants , officials say . Houthis , al Qaeda have been fighting in Yemen for months .