A suicide bomber detonated an explosives belt near a football stadium in the southern Yemeni city of Aden, killing at least four people, witnesses have said.
Eight people were wounded in the attack on Tuesday, which appeared to target young men queuing to sign up for the military.
The witnesses told the Associated Press news agency that the four people killed were in addition to the bomber.
The attack comes during a ceasefire, and a day before peace talks aimed at ending more than a year of war in a country that has become a subject of dispute for regional powers Saudi Arabia and Iran.
A UN spokeswoman, Stephane Dujarric, on Monday said the truce appeared to be holding despite "pockets of violence".